That's the case for a lot of pro-football players. But when the battle on the field comes to an end, the battle with their weight is just beginning.
Nate Newton weighed 335 pounds when he played for the Dallas Cowboys.
"I was one of the biggest linemen they ever had," he said.
Steve McKinney was a 300-pound offensive lineman for the Texans.
"I was probably eating somewhere around 4,000, 3,500 calories a day," McKinney said.
And N. D. Kalu was 285 when he played defensive line in Houston.
"I was always trying to gain weight," Kalu said.
Each was required to be massive. But when their NFL careers ended, their struggles with weight began.
"I went from being around 360, to now I'm 397, I'm 411 pounds, I'm 420 pounds," Newton said.
Newton's bad habits of binging on french fries and beer didn't stop until a triple tragedy; within six weeks, his father and two aunts died. At the time, he weighed more than 400 pounds and he took it as a warning.
"I look at my kid, I'm like, whoa man, he's 11 and I'm like, I'm not gonna see my kid get to 20," Newton said.
Newton underwent gastric weight loss surgery. He changed his diet, began exercising regularly, and in the last two years, has lost a staggering 170 pounds.
"They're starting off at a weight that is almost unnatural," Newton's bariatric surgeon Dr. David Kim said.
Dr. Kim sees more and more former pro-football players desperate for change.
"I think it takes a lot for an NFL lineman to say, hey I need some help," Dr. Kim said.
"I was eating Snickers, Reese's, Butterfingers, just whatever I wanted just to pack on weight," McKinney said.
McKinney didn't realize how bad his eating habits had become until his pro-football career ended.
"Can't play with my kids for more than 30 minutes without wearing out. This is not right, I used to be a professional athlete, I should be able to do this," he said.
Today, he watches what he eats.
"Nobody ever said you have to feel stuffed after every meal either," McKinney said.
In a few months, he's lost 50 pounds.
"It was amazing how fast that weight started to come off," McKinney said.
For Kalu, losing weight would mean avoiding fast food, something he thrived on during his playing days.
"I enjoyed it so much but yet I was as fit as could be because of the training," he said.
He retired and the training stopped, but the weight gain didn't.
"When the doctor told me that I need to lose 20 pounds, that kinda hit home because I've never been told I need to lose weight," Kalu said.
Kalu's solution was to cook. He prepares healthy meals on the weekends and stores them for the week ahead. He's lost 15 pounds so far.
"What I would tell players that are currently playing now, start changing your habits now so you get used to it," Kalu said.
Newton's transformation is by far the most dramatic and is often a topic on his radio show in Dallas. A new career, he says, for a new man.
"If you're not going to work out and you're not going to try to eat better, then you're wasting your time, just stay fat and die," Newsome said.
They lost weight in different ways, but all three of these former pro players had to make the same choice: change their diet, so they could change their life.