Who is making it? Who is not? We've concocted retirement scorecards for some showcase retirees in entertainment, politics and sports. See the full list here.

Winner: Billie Jean King
Former occupation/notable position held: Multi Grand Slam-Winning Pro Tennis Player
Activities during retirement: Gender equality advocate; Olympic Coach; Goodwill Ambassador
Retirement Report Card Grade: A

One of the toughest things about retirement is the initial transition. It's a disruptive life change that many don't realize ranks with the likes of childbirth and divorce until they're right in the middle of it themselves.

Transition wasn't a problem for 39-time Grand Slam champion Billie Jean King. She was transitioning "on the fly" even at the peak of her career by semi-retiring, one step at a time. She immersed herself in issues like gender equality, prize money parity for athletes, and the rights of female athletes to unionize. Her legendary "Battle of the Sexes" victory against Bobby Riggs, televised in primetime by ABC, was more than women's rights-era spectacle: It ushered in the modern era of women's pro sports.

King's leadership among players in supporting the Virginia Slims tour, which brought real money to women's tennis for the first time, is more typical of someone with over-the-hill status in a sport, not a player in her prime. The same goes for King's role in helping found (and later, leading) World Team Tennis, an arena-sized attempt to capitalize on tennis's huge popularity in the '70s.

King seems to have carefully calibrated her career to remain vital to, and in, the sport she loves for as long as there is mutual benefit. That's a taut tight rope walked by precious few.

After tackling gender and pay activism – and coming to grips with eroded skills – King successfully transitioned to coaching. In the mid-1990s, King became the captain of the United States Fed Cup team and coach of its women's Olympic tennis squad. She guided the U.S. to the Fed Cup championship in 1996 and helped three players capture Olympic gold. She came to grips with her sexuality, now speaking about it publicly and inspirationally, after long resenting having been "outed" years ago.

In 2006, the USTA National Tennis Center in New York City was rededicated as the USTA Billie Jean King National Tennis Center. The center is the largest sports facility in the world to be named after a woman. An honor rather befitting this Grade A retiree.

Michael Burnham is CEO of My Next Phase, a consulting firm offering non-financial retirement planning products and services (www.mynextphase.com).