(CBS) — For years, video games have been blamed for turning kids into lazy couch potatoes. But Monday’s launch of Nintendo's "Wii Fit" has players on the move. The fitness phenomenon made its mark in London months ago.

New mom Kelly Nicholls doesn't get much 'me’ time since Ella was born.

So any me time is usually Wii time — it's Nintendo's new fitness video game.

“After Ella was born, I wanted to lose the baby weight,” she told CBS News.

Now she's a self-confessed Wii Fit fanatic. She says she's lost five pounds in three weeks with activities ranging from step class to snowboarding.

The $90 game comes with a balance board that senses every tiny movement, controlling a character on screen. It weighs you and charts your progress, too.

She does about 30 minutes a day, every day, and says her friends often drop by for their fix, too.

“I've had some people come over, I don't think they want to see me — they just want to go on the board now!” she said.

Making fitness fun has always been the challenge, and while Wii Fit has been a huge hit — the pros say just remember to keep it in balance.

“It's something that needs to be used with guidance,” explained personal trainer James Mitchell. “I certainly wouldn't suggest people exclusively use the Wii Fit as their entire fitness regimen.”

But he's even told his clients it's not a bad tool to get the heart rate pumping

“Anything that encourages people to be more active and you know, move around, I think is a great thing,” Mitchell said.

The Wii has sold millions worldwide and is just beginning its sprint across America. Nintendo's hoping the fun factor will ensure their Wii doesn't fall by the wayside as just another fitness fad.