Michael Phelps: Everything is coming back to me

(CBS News) In an interview to be broadcast Sunday night on "60 Minutes," swimming star Michael Phelps tells Anderson Cooper he's feeling like his old self again.

Phelps is back in the pool, preparing for this summer's Olympic Games in London. Four years ago, Phelps was the sensation of the Beijing Olympics, winning eight gold medals.

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Phelps was photographed in 2009, apparently inhaling from a marijuana pipe, leading some to question if his focus had faltered. But these days, Phelps said he's swimming races like he used to. "Everything is kind of coming back to me, what it was, I guess, before 2008."

Every race in London will be compared to what Phelps accomplished over nine days in the summer of 2008.

Phelps and Cooper previously sat down in 2009 for "60 Minutes" when the swimming star was fresh off his stunning wins in Beijing. Watch that interview here.

When asked in the latest interview with Cooper if he's been able to absorb what he did in Beijing, Phelps said, "No. I guess I probably do get kinda like choked up like just thinking about all the memories and thinking exactly when I touched the wall, what was going on in my head. "

When he retires from swimming, Phelps will only be 27 years old.

Watch the full interview Sunday night on "60 Minutes."