Over his 12-year career, three-time NBA All-Star Antoine Walker made more than $108 million. But just two years after retiring from the league, he'd lost it all.
"It was my darkest hour," Walker told CNBC, describing the day he filed for Chapter 7 bankruptcy in May 2010. At the time, he had about $4 million in assets and more than $12 million in debt.
His over-the-top spending combined with gambling losses and real estate investments that tanked in 2007 had left him with nothing.
Instead of burying his past under the rug, the NBA champion has made it his life's mission to educate others about financial responsibility. Walker is now a consultant for the Morgan Stanley Global Sports & Entertainment financial literacy initiative, which educates college and professional athletes on money management.
He shared some of the hardest money lessons he learned on his journey.
If you've reached a major financial milestone for yourself or have accumulated wealth in a short amount of time, protect it, Walker said.
"You worked so hard to get to this point," he told CNBC. "Don't blow it. Don't blow the money that comes with it."
"Remember how hard it was for you to get to that level," he added. "Take care of it. Build your team, make sure you preserve it."
Walker learned the hard way how important it is to set boundaries.
"It's a tough lesson to learn," he said. "I wanted to take care of my family; I wanted the best for them. I really didn't have the word 'no' in my vocabulary. It was something I was not used to saying."
When you come into money and everyone is coming to you with requests, "you've got to get the word 'no' in your vocabulary," he added.
Walker described the pressure some NBA players feel to spend lavishly and drive the same expensive cars as veteran players. He admitted to having a "car fetish" himself, and also said he grew accustomed to spending excessively on designer clothes.
"Create a lifestyle where you're going to have generational wealth," Walker said.
"Put together a savings plan where you'll be okay for the rest of your life before you start this lavish lifestyle."
For Walker, speaking about his financial mistakes has been a chance to respond to media criticism over his spending habits, as well as make a difference.
"If I changed two or three kids' lives, I think my life is a success," he said.