The 253 players who were drafted two weeks ago enter the NFL with the wrong impression.

For four months they’ve been fawned over by teams and media, jetting around the country to meet with famous coaches and reporters. They were celebrated at their colleges and hometowns, and a few got to walk a red carpet and be the center of attention on a glitzy night at the NFL Draft.

Guess what, rookies — you’re not the star of the show anymore. Now you’re just a lowly, unproven grunt, fighting with 89 other players for only 53 roster spots. Those of you drafted in the first four rounds probably have a roster spot locked up for this year, but nothing else is given — not playing time, your spot on the depth chart, or your role with the team in future years.

And for the several hundred of you drafted in the late rounds or not drafted at all, you’d better dedicate 100 percent of your life to making the team, because the odds are stacked squarely against you.

Life as a professional is a dramatic shift from life as a college athlete. There are no 20-hour-per-week practice limits anymore, no athletic department employees to help you with life off the field, and a lot more responsibilities with your finances and life as an adult in general.

With five weeks of the offseason program to go, and training camp just three months away, here is some advice for rookies to integrate into the NFL culture, maximize their potential, and work their way into the good graces of their coaching staff. Helping us create this list are former player Damien Woody, two player agents, an AFC personnel executive, and our own observations from nine years of covering the NFL:

■ Football is your life now. Many rookies have never had to work too hard to excel at football. They were often the biggest, strongest, and fastest player at every level, and their natural ability got them to the NFL.

But natural gifts won’t take them very far in the NFL without total dedication. This is the golden opportunity to make life-changing money and forge a long career, and their job needs to be their top priority — not partying, spending money, playing video games, or any other temptations they got away with in college.

“Be a pro — this is pro football,” the AFC executive said.

Players are observed all day long by their bosses — how they approach their workouts, how much film they study, whether they goof off in the film room, and so on. The executive pointed out a few specific key areas of observation:

“Learn — get in the classroom. No mental errors,” he said. “Competition — this is the best of the best. You still need to make the team or carve out a role on the squad. Only 53 guys will make the team in September.

“Conditioning — have your body ready to compete at the highest level of the game. And consistency — demonstrate it every day. Eliminate the ups and downs.”

And all those football clichés hold true.

“Show up early, stay late, STAY IN THE FILM ROOM!!” was one agent’s No. 1 advice. “Study the playbook/iPad all the time.”

Living near the team facility is an easy way to make sure you can arrive early and stay late for workouts and film study.

■ Treat your body above all. Most rookies have never had to worry much about their bodies. The hits they took in college aren’t as bruising as in the NFL, and their metabolisms work so fast that they can burn off that Big Mac in no time.

But body maintenance and injury prevention is the most important key to NFL success. The season is 1-2 months longer than it was in college, and those hits take a big toll on your body.

“Take care of your bodies early and often,” Woody said. “Too many times young players take for granted their youth and aren’t proactive in preventative treatment from the rigors of football.”

Learn to love the cold tub. Ditch the Big Macs and eat more salads. Limit your alcohol intake and aim for 8-10 hours of sleep per night.

“It’s not as fun and takes a lot of discipline, but your body will thank you come December and January,” another agent said.

■  Rent, don’t buy. The average NFL career is about three years, and the odds of having a long, productive career with one team are minuscule. There’s no need to sink a significant portion of your signing bonus into a big, new house right away. Even top draft picks should wait to buy a home. Who knows how long you’ll stay with your current team?

■ Limit your big purchases. Nothing drives me crazier than seeing a sixth-round pick wearing expensive new jewelry or a practice squad player carrying the entire line of Louis Vuitton luggage. There’s no harm in treating yourself to one or two finer things, but most rookies aren’t making life-changing money and need to realize that this money is really just a good starting point in life. They’ll be much better off in the long term by simply sticking their money in a savings account or an index fund.

“Lease a car, rent an apartment, don’t buy jewelry, don’t give ridiculous amounts to your family, and don’t buy tickets for everyone and everyone for every game,” the first agent said.

Cardinals rookie pass rusher Robert Nkemdiche said before the draft that he wants to buy a pet panther. That’s as much of a red flag as any failed drug test or off-field issue.

■ Learn how to say no. This is the toughest and probably most important lesson for rookies. Every uncle, cousin, and long-lost friend from middle school will reacquaint themselves with you now that you’re in the NFL. Predatory lenders and investors will try to dazzle you with offers.

Learn to approach each person with skepticism.

“The transition into the NFL is hard enough as is,” Woody said. “But you’ll have family, friends, random people coming at you for money, business opportunities, favors — things that cannot only harm your long-term financial viability but distract you from the job at hand.”

LOWERING THE RISK

Pay cuts part of teams’ prudence

Julio Cortez/Associated Press/File 2015

Victor Cruz signed a new three-year deal this offseason that guarantees him only $2.4 million, his 2016 base salary.

Patriots receiver Danny Amendola went through a humbling experience last week, as millions of football fans across the country became privy to the fact that he took nearly a 75 percent pay cut to stay with the Patriots for 2016.

But Amendola is in good company in the NFL, where contracts never are what they seem. He can join a support group with some of the biggest names in the league, who also have had to face the ignominy of a pay cut this offseason to stay with their teams.

Remember when the Chiefs’ Tamba Hali was one of the most fearsome edge rushers in the NFL, collecting 55 sacks and four Pro Bowl nods between 2009-13? Now he’s 32, and the Chiefs made him “restructure” his contract for the second straight year. Last year he took a pay cut from $9 million to $6 million. This year he signed a new three-year deal that does guarantee him $11.5 million, but it’s spread out over the next two seasons. The Chiefs also tied $1 million in Hali being healthy and active, $500,000 for attending offseason workouts, and $1 million for making weight five times during the season. That last clause illustrates that the Chiefs believe Hali needs to remain motivated to stay in shape during the season.

Remember when Victor Cruz was the hottest young receiver in the NFL, catching 241 passes for 3,626 yards and 23 touchdowns between 2011-13? Well, Cruz hasn’t played a game since tearing his patellar tendon in the sixth game of 2014 (he also had a calf injury last year), and the Giants slashed his pay this offseason in a pay-for-performance type of contract.

Cruz was due to make $8 million this year and $24 million over the next three, but signed a new three-year deal this offseason that guarantees him only $2.4 million, his 2016 base salary. He can make a maximum of $8 million this year, but only if he stays healthy (he will make $187,500 every game he is active) and productive (he has $2.5 million tied up in incentives). And Cruz doesn’t have anything guaranteed for 2017 or 2018, making his contract a true year-to-year proposition.

The Dolphins celebrated a new two-year contract for Cameron Wake last week, and while it guarantees him $3 million next season, they took $1.25 million of his salary and converted it into incentives. And Cowboys cornerback BrandonCarr impressively made it through four years and about $40 million of his deal, but now that he’s on the older side (he turns 30 next week), the Cowboys cut his 2016 salary from $9 million to $5.5 million with another $500,000 in incentives.

CONCUSSION QUANDARY

Varga’s situation a test in treatment

Darron Cummings/Associated Press/File 2015

Tyler Varga returned six kicks for 151 yards last season for the Colts.

Last week, the Indianapolis Star ran a must-read, in-depth story on Colts fullback Tyler Varga, the former Yale running back who is slowly coming back from a scary concussion last season.

Varga took a hit on a kickoff against the Jaguars in Week 3, exited the game, woke up the next day feeling like he had the flu, and tried to convince himself that it wasn’t a concussion. But the headaches, dizziness, and confusion wouldn’t go away, he had blanks in his short-term memory, and he couldn’t pass the concussion tests for several weeks.

The Colts’ doctors tried to prescribe Varga Amantadine, a drug that is commonly prescribed for Parkinson’s disease but is also sometimes prescribed for concussion-like symptoms. Varga told the Star that the Colts encouraged him to take Amantadine, but Varga’s own research found that the drug can create psychotic reactions like schizophrenia, so he declined to take the medication.

About an hour after Varga told the Colts he wasn’t going to take the medicine in October, they placed him on injured reserve, ending his season. Varga said he is fine now, and plans to play in 2016, but he didn’t feel like himself until February, four months after the concussion.

Two thoughts on this story:

■ One of the more fascinating angles revolves around Varga’s treatment, and the evolving opinions from the medical community about how to treat concussions.

Varga was initially told to stay in a dark room and refrain from mentally-taxing activities — the “cocoon method” that is common for treating concussions. But Dr. John Leddy of the University at Buffalo’s Concussion Management Clinic said mental stimulation might be the best way to overcome concussion symptoms. Varga said he didn’t start to feel himself until he took an internship last winter at the Yale Investments Office as a financial analyst.

“It’s important for someone to rest initially, but we know that activity and exercise are good for the brain. It helps it heal and balance the nervous system,” Leddy said. “When people are having a prolonged recovery, telling them to rest until the symptoms go away is exactly the wrong thing to do.”

■ I worry that Varga’s decision to go public with his story, which doesn’t paint the Colts’ doctors in the most flattering of light, could have a retaliatory effect from the team. Varga is a fringe player fighting for a roster spot, and revealing private details and speaking out against the team at best can’t help his chances, and at worse could tip the scales against him.

ETC.

Manning back in game — sort of

Jim Davis/Globe Staff/File 2014

Peyton Manning is well-versed in Adam Gase’s offense.

Peyton Manning couldn’t stay away from football for long. Manning, who retired in February after winning the Super Bowl, spent a little time with Dolphins quarterback Ryan Tannehill at the team’s facility this spring to give Tannehill a few tips on Adam Gase’s offense before Tannehill was allowed to interact with his coaches. Gase, the Dolphins’ new head coach, spent three years with Manning in Denver.

“It was really cool,” Tannehill told the Miami Herald. “It was really cool just to be able to sit and pick his brain about things he’s done in this offense and football things in general: snap counts, things you like, the way you want guys to run routes, little details about the game. We really just got to talk the game, which is something we both love.”

If you’re wondering what Manning was doing in Miami, he and his wife own a condo in South Beach and spend a few months of the offseason there every year. Given his ties to Gase, and owner Stephen Ross’s well-known affection for Manning, it makes sense that Manning was invited to the facility to hang out and talk football.

Extra points

THIS is why 78 will never be worn again on the Bills.

Bad things, man. #BRUUUUUUUCEhttps://t.co/qCWh3Fu96G

— Buffalo Bills (@buffalobills) May 11, 2016

Cool gesture by the Bills to retire Hall of Fame defensive end Bruce Smith’s No. 78 before their home opener against the Jets in Week 2. Smith will become just the second player to have his number retired by the Bills, joining Jim Kelly’s No. 12. Retiring a jersey is a big deal in the NFL, given that there are only 99 numbers and teams need 90 of them for the preseason. Along those same lines, it’s neat to see the Patriots keep Jerod Mayo’s No. 51 out of the rotation and the Seahawks not give Marshawn Lynch’s No. 24 to any player this year. Great sign of respect . . . Ravens left tackle Eugene Monroe donated $80,000 to researchers at Johns Hopkins and the University of Pennsylvania to help endow a series of studies to examine the impact of cannabinoid therapies on current and former NFL players. Monroe believes that cannabidiol and marijuana can help for pain management and chronic traumatic encephalopathy, and hopes that his actions will influence the NFL to remove marijuana from the league’s list of banned substances . . . The Seahawks might have the shortest group of quarterbacks in the league. Russell Wilson is only 5 feet 11 inches, backup Trevone Boykin is 6 feet, and third-stringer Jake Heaps is the giant of the group at 6-1 . . . The buzz of the Raiders potentially moving to Las Vegas continues to grow, but we’re still having a hard time buying it as anything more than leverage against the city of Oakland. Former Giants coach Jim Fassel, who coached the Las Vegas Locomotives of the former UFL from 2009-12, told SiriusXM NFL last week why he doesn’t think the NFL will come to Vegas. “Casinos don’t want patrons at the stadium,” he said. “They want them gambling.” And in Vegas, the casino owners get what they want.

Getting a leg up

The Buccaneers traded up to select placekicker Roberto Aguayo in the second round (59th overall) of the NFL Draft. He is the ninth kicker to be taken in the first or second round since the merger, and the majority of them had productive careers.

Compiled by Michael Grossi

Ben Volin can be reached at [email protected]. Follow him on Twitter @BenVolin. Material from interviews, wire services, other beat writers, and league and team sources was used in this report.