Michael Phelps will retire after London Olympics (VIDEO)

Michael Phelps is training hard again. It's true he was a party animal after the last Olympics. After his new found celebrity stature. He hung out with everyone, some good some.....uh not so good. After an interview on 60 minutes, Michael Phelps is done.

"Once I retire, I'm retiring," he told Anderson Cooper. "I'm done."

The wide-ranging interview also touched on Phelps' training, charitable efforts and life in the spotlight. In it, the 16-time medalist confirmed what many had suspected -- that he was burnt out after his Beijing triumph and needed time to recharge before the long haul to London.

"It was hard, because I didn't know if the passion or the fire was still inside of me," Phelps told Cooper. "And it took awhile for me to actually realize it myself. [Coach] Bob [Bowman] couldn't tell me, my mom couldn't tell me. They couldn't help me find it."

His coach was evasive when asked about Phelps' chances in London. He won two individual golds and two silvers at last summer's world championships while in lackluster shape, but should do better in London because he is in better shape.

****Other revelations in the interview: Phelps sleeps in a chamber that simulates being at 8,500 feet, he carries his Beijing medals in a purse and he likes to take "Hangover"-inspired trips to Las Vegas.