Sports Illustrated estimates that 78 percent of NFL players go broke within two years of retirement, and 60 percent of NBA players go broke within five years of retirement. Studies show that the average NBA career lasts 4.8 years, and the average NFL career lasts just 3.3 years. That means that many players will need to find a second career before they even turn 30. That's why a number of pro athletes are using their down time to pursue internships and job opportunities at some of today's top companies. In 2017, New York Jets linebacker Brandon Copeland opened up about his off-season gig as a part-time analyst for the asset management firm Weiss Multi-Strategy Advisers. "It's guaranteed football is going to be over one day," he told ESPN. Copeland spent two summers in college interning for UBS, and the firm's founder says he'll "hire him in a second when his NFL career is over." Here are five professional athletes using internship opportunities to set them up for success after sports:

1. Andre Iguodala

Andre Iguodala #9 of the Golden State Warriors Andrew D. Bernstein | NBAE | Getty Images

Internship: Bank of America Merrill Lynch During the 2011 NBA lockout, Andre Iguodala spent his down time completing a week-long internship with Bank of America Merrill Lynch. He told Yahoo! Sports that during the internship he shadowed a venture capitalist and visited the New York Stock Exchange. He says he's always had an interest in finance and was curious to learn more. "Being an athlete, I've been blessed with an opportunity to make a good living and be able to hold on to a good amount of wealth," he said. "I understand that this basketball thing is a small window. The things that I'm getting from basketball … I want to stretch it out my whole life." Now, as a star player for the Golden State Warriors, Iguodala has shifted his focus to tech. In 2015 he told CNBC he was taking full advantage of his team's proximity to Silicon Valley. Already, he says, he's made investments in top tech companies like Facebook, Twitter and Tesla.

2. Jaylen Brown

Jaylen Brown of the Boston Celtics looks on during Game Seven of the 2018 NBA Eastern Conference Finals. Maddie Meyer | Getty Images Sport | Getty Images

Internship: Base Ventures Boston Celtics player Jaylen Brown may be early in his NBA career, but already the 21-year-old is thinking about life after basketball. The star athlete, who has an interest in tech, has already completed an internship with venture capital firm Base Ventures and hosted a tech summit to teach other players about opportunities outside of sports. "My thought process is to just educate athletes and people around you about what is really going on, especially basketball players," Brown told ESPN's The Undefeated. "A lot of people wait until the end of their careers to really get things going. I thought it would be more beneficial to start early, put your foot in the door and start educating yourself, because technology investments are where the real money is at."

3. Anthony Walker

Indianapolis Colts linebacker Anthony Walker on the field before the NFL preseason game between the Cincinnati Bengals and Indianapolis Colts on August 31, 2017. Icon Sportswire | Getty Images

Internship: Miami Heat corporate office Indianapolis Colts linebacker Anthony Walker wants to one day be the general manager of a professional sports team. That's why the 23-year-old recently spent his off-season interning for the NBA's Miami Heat. Earlier this year, he told Fox Sports that he spent four weeks getting a crash course on what it takes to run the business operations of a basketball team and how to execute off-site events. "For me, it's about trying to get the other side of sports," said Walker, who studied business management with a focus on sports and marketing at Northwestern University. "Football's going to end for me at some point. I want to be able to use the networks I have now to help me in the future for when I do need to find something else to do with my life. And you never know when that's going to come."

4. Harrison Barnes

NBA star Harrison Barnes Thearon W. Henderson | Getty Images

Internship: Facebook While playing for the Golden State Warriors in 2014, NBA star Harrison Barnes interned for social media giant Facebook. He told Mashable that he would drive 40 minutes from his home in Oakland, California to Facebook's headquarters in Menlo Park to work with and shadow employees for one week. "There's going to be a time when the ball stops bouncing and you have to move on to something different, whatever that is," Barnes, who now plays for the Dallas Mavericks, told Mashable. "But I just know I've loved being involved with technology and social stuff these past two years."

5. Torrey Smith