Steve Young has had tremendous success since his retirement from the NFL in private equity.

Young co-founded a firm called HGGC a decade ago that specializes in acquiring majority stakes of enterprise software companies worth $300 million to $500 million.

HGGC uses Young's moonlighting job on ESPN's Monday Night Football as marketing events. Young and his partners buy a luxury suite for virtually every Monday matchup to meet with portfolio companies, acquisition targets and customers. 

HGGC has generated an average annual yield of 66 percent over the last three years, according to a firm presentation obtained by Bloomberg News.

Young says he would have had to quit his job with ESPN years ago if not for the fact that his partners like him to keep a high profile.

“My wife hates football, and my kids don’t really care,” Young says. “I see myself as a deal guy first. I’ve put football behind me. Roger Staubach once told me—and I’ll never forget it: ‘When you retire, run. Never look back.’ ”

During his NFL offseasons as a player, Young pursued a law degree at BYU. Young was forced to retire from the NFL in 1999 after suffering his seventh official concussion.