The NFL draft kicks off tonight, which means that some athletic young men in their early 20s are about to earn some staggering salaries.

For example, last year's first overall pick, the Tampa Bay Buccaneers' Jameis Winston, signed a four-year contract worth more than $25 million. But high-profile rookies like Winston are the exception, rather than the norm. For every Winston, there's an obscure, undrafted rookie earning the league minimum: A salary of $435,000 in 2015, which will rise to $450,000 this season.

Of course, no one is holding a pity party for a young person making so much money. But the smartest NFL rookies have become wise to a harsh reality about their gaudy salaries: The money doesn't last long. Research published earlier this year in The Wall Street Journal showed that 15 percent of NFL players declare bankruptcy after they retire. The study included more than 2,000 players--all of those drafted by the NFL from 1996 to 2003. What's more, the study found that bankruptcy did not depend on how much a player had earned in his career. No amount of money is immune to mismanagement.

Thanks to the data in studies like this, many NFL players now live quite frugally, despite their hefty paychecks. For example, last year's Washington Redskins team was notorious for how its players were scrimping and saving. According to The Wall Street Journal, quarterback Kirk Cousins drove a dented GMC Savana passenger van to work and shared an apartment with offensive lineman Tom Compton. Running back Alfred Morris (now with the Dallas Cowboys), who made a base salary of $1.5 million last year, rode a bike to work. When the weather wouldn't cooperate with biking, he drove a 1991 Mazda 626. Pass rusher Ryan Kerrigan shares an apartment with a roommate in suburban Virginia--even though Kerrigan is on a five-year, $57.5 million contract.

These are far from the only players who understand the importance of saving money. According to a story on ESPN.com, wide receiver Ryan Broyles, formerly of the Detroit Lions, lived on a budget of $60,000 a year during the first three seasons of his career. The rest of his money--he signed a four-year, $3.6 million deal after being drafted in 2012--is earmarked for investments and retirement.

More and more, players are setting budgets for themselves--even superstar players. For example, recently retired running back Marshawn Lynch hasn't spent a penny of the nearly $50 million he earned in salary during his career. He has lived off earnings from endorsements. New England Patriots tight end Rob Gronkowski has taken the same approach, not spending any of the more than $16 million in salary he has earned so far.

Why are more players hip to the financial realities? One reason is the NFL itself, which provides financial educations to the rookies during educational symposia, prior to their first seasons. Along with TD Ameritrade and the University of Miami School of Business Administration, the NFL holds annual seminars devoted to financial fitness. One of the speakers is Pat Kerney, who was the NFC Defensive Player of the Year in 2007. "He's not so far removed from football and the casual lingua franca of playing life, and his keynote could have been delivered at midfield in a practice," notes The Wall Street Journal. Kerney doesn't just focus on investing strategies, either. He cites the cost of living in various NFL towns--how living in, say, Charlotte, North Carolina, costs a lot less than living in Seattle.

While some attendees are high-profile draft picks, every year there are players who have entered the league earning NFL minimums. One of them, New York Jets linebacker Josh Martin, summed up the savings mindset: "I have to think about life beyond football," he told the Journal. "Reality hits you quick, so you have to maximize your money."