Michael Phelps: Ready for London games?

The Olympic gold swimmer is back to a strict training regimen after a lull that included skipping practice and uncertainty about returning to the games

Michael Phelps made history when he won eight gold medals at the Beijing Olympics in 2008. Now he's training hard, driven to make a splash in London this summer. He's just three medals shy of breaking the record for most Olympic career medals. But the road back to the Olympics hasn't been easy, Anderson Cooper reports. The usually competitive and motivated Phelps went through a slump that made his own coach wonder if the swimmer would make it to the London games for the last lap of his career.

The following script is from "Michael Phelps" which originally aired on May 6, 2012. Anderson Cooper is the correspondent. Draggan Mihailovich, producer.

In three months, Michael Phelps will climb onto the starting block for his final races at the Summer Olympics in London. When we last interviewed him on 60 Minutes in the fall of 2008, he had just made history, winning eight gold medals at the Beijing Olympics.

Phelps was riding a worldwide wave of awe and popularity. It seemed there was nothing left to accomplish. So why continue swimming? Phelps has often wondered the same thing over the last three years. It's been the most difficult period of his career. He was photographed at a party with a marijuana pipe and, it may surprise you to hear that his passion for swimming seemed to have faded. But now, as he approaches the last lap of his career, with another Olympics in sight, Michael Phelps is once again training hard, once again ready to make history

It's 6:20 on a Saturday morning in March, virtually alone on the streets of his native Baltimore, a groggy Michael Phelps is off to another grueling daily practice in his 16th year of Olympic training. He hasn't been this committed since the Beijing Games.

Michael Phelps: After Beijing, I mean, there's countless times where I've just wanted to be like, "I don't want to do this anymore. I don't want to go to the pool every day."

Anderson Cooper: So now is it, is it hard getting out of bed in the morning?

Michael Phelps: No, because one, we're so close. And two, because I'm actually enjoying it. I'm swimming well again.

With the London Olympics looming, Phelps has been rejuvenated. Physically over the last year, he's become more powerful than he was in Beijing. He's focused on weight training like never before. Gone is the grumpy, disinterested swimmer of the last few years who desperately wanted to trash his alarm clock. Back is a sense of urgency. Bob Bowman is Michael's longtime coach.

Anderson Cooper: How does his shape now compare to the way he was a year ago?

Bob Bowman: Oh, much better, much better. A year ago, on a scale of one to 10, was a two. This is a nine, eight or nine.

Anderson Cooper: Two?

Bob Bowman: Yeah, oh yeah...

Anderson Cooper: I mean, that...

Bob Bowman: That was a low, really low.

Anderson Cooper:/How worried were you?

Bob Bowman: Very worried, at that point.

Anderson Cooper: What was the fear?

Bob Bowman: That we had so far to come, he couldn't get back.

It's hard to imagine Michael Phelps not being in shape. But after his exploits in Beijing, he stopped training and started living.

By early 2009, Phelps had a decision to make: retire for good...or to jump back into the pool for a fourth Olympics and years of early morning workouts.

Bob Bowman:I thought it was a 50-50. I really didn't have a feel for whether he would come back or not come back.

Debbie Phelps: I'm like, 'Either do it or don't do it'...