Swimming great Michael Phelps revealed that he has battled severe anxiety and depression for much of his life which drove him to consider suicide after his success at the 2012 Olympics.

Speaking at a mental health conference in Chicago on Tuesday, the 23-time Olympic gold medal winner talked openly about his long battle with crippling depression and is encouraging others to get help like he did.

"After every Olympics I think I fell into a major state of depression," the 32-year-old Phelps said.

Phelps said he reached rock bottom following the 2012 Olympics in London where he won four gold medals and two silver. For four days he remained in his room without food or sleep.

"I didn't want to be in the sport anymore," he said. "I didn't want to be alive."

When he hit a low point in his depression, Phelps said, "You do contemplate suicide."

Over the past two years Phelps has opened up about his struggles.

"We're supposed to be this big, macho, physically strong human beings, but this is not a weakness," he said. "We are seeking and reaching for help."