The daily routines of some of the world's most successful people — from Richard Branson to Oprah Winfrey — include a morning workout. And Olympic champion swimmer Michael Phelps is no exception. In fact, the star athlete says exercise helps him be more successful.

"Being able to just get out there and sweat is something that I need," Phelps tells CNBC Make It. "So I kind of have to make sure I get that little bit of time, whether it's 20 or 30 minutes, to myself. Just to get ready, to get prepared so I can be a better dad, a better husband, a harder worker."

Though Phelps has retired from swimming, he's still incredibly busy as an entrepreneur. So when he's on the road, "it's workout first thing in the morning," Phelps tells CNBC Make It while in New York City promoting his role as global ambassador for Colgate's Save Water campaign, which aims to spread the message of water conservation with small, behavioral changes such as turning off the faucet when brushing your teeth.

"It's either riding a bike — 45 [minutes], an hour on a bike — 45 to an hour on an elliptical. I might swim every now and then. I just started lifting again.

"I try to do different things that I didn't do throughout my career, so I don't get bored," he says. "That's one thing I always have to change."

When Phelps is at home in Arizona however, his days move at more relaxed pace, and so does his morning routine. Phelps says he usually gets up at around 6:30 a.m and feeds his kids Boomer, 2, and Beckett, 1. (He and wife Nicole also have a third on the way.)

"I'm usually in charge of breakfast in the morning, so it's whatever the boys want," Phelps says.