In 1969, Heisman Trophy winner and Navy veteran Roger Staubach joined the Dallas Cowboys as a 27-year-old rookie with a starting salary of $25,000 a year (a far cry from today's rookie minimum salary of $610,000).
In 1979, by the end of his 10 seasons with the Cowboys — which garnered him two Super Bowl wins, five appearances and an NFL MVP title — Staubach was making around $160,000 a year. (For comparison, NFL star O.J. Simpson was making around $806,668 that year.)
But today, Staubach, 78, is one of the wealthiest NFL players in history with an estimated net worth of $600 million, according to Radio.com — thanks to a side hustle he started during his off-seasons.
After his rookie season in 1970, Staubach worked as a real estate broker for Henry S. Miller Co., one of the largest independent commercial real estate firms in Texas at the time.
"I was 27 and we had three children," Staubach told Forbes in 2014. "If I got hurt, I knew I had a family to provide for, and it was not crazy money in the NFL then."
His part-time gig lasted for seven years until he went out on his own and started a commercial real estate business, The Staubach Company in 1977.
Over the next three decades, Staubach developed a strong client base to help tenants find office, retail and industrial space. By 2008, the company had more than 70 offices in North America and 1,600 employees. That year, Staubach sold his company to Chicago-based real-estate brokerage firm Jones Lang Lasalle for $613 million.
During a 2010 during a real estate luncheon, Staubach said he "learned a lot about teamwork and resiliency and perseverance in football" and translated well into business.
Staubach credits both his on-and off-the field success to focusing on others people's needs, not just his own.
"I think my parents really made me recognize the importance of somebody else, other than yourself," Staubach said in an interview with The Slate published Sept. 4.
In both football and business, Staubach said he learned to balance getting things done and "not being a real jerk" at the same time.
"But, you have to demand things from people and you have to be grateful for how things are done," he told The Slate.
He added that the most important thing you can do when you're building a business is to "make sure it's diverse" and the "opportunities are there."
"I think the most important thing of all is balance. You take from life, and you give back," he said. "If you are truly balanced, you look at giving back."
This story has been updated to reflect that Staubach served four years in the U.S. Navy after graduating from the Naval Academy in 1965.