Before the age of 20, he had won the NCAA basketball championship and was selected by the Boston Celtics as a top pick in the 1996 NBA Draft. Walker quickly became a basketball superstar. He was named to the All-Star team three times and won the top prize in pro basketball with the Miami Heat in 2006.

Thanks to his on-the-court success, Walker made more money playing the sport he loved than he could even dream of when he grew up in a poor Chicago neighborhood.

But like many professional athletes who experience a sudden explosion of wealth, it was all gone in an instant. Despite pulling down more than $108 million during his career, Walker filed for Chapter 7 bankruptcy in 2010, just two years after retirement.

“I thought I was set for the rest of my life,” Walker told CNNMoney. “My story is sad. It’s sad to see other guys work so hard throughout their life — and then they just lose it in two or three years.”

That’s why Walker, now 38, is now working to steer young athletes away from the mistakes he made. Walker and former NFL linebacker Bart Scott recently teamed up with Morgan Stanley Global Sports & Entertainment to bring real-life lessons to today’s players.

But first Walker had to figure out how he went from fat NBA paychecks to financial rock bottom.

Got the drop at CNN Money . . .