You can do cardio intervals just about anywhere, as we’re discovering during this month’s fitness challenge: your living room is a classic, or you can hop on a bike or lace up your running shoes. But ...

LAGUNA NIGUEL, Calif. (KABC) -- These people are talking about a new class called FIRE. "It's such a great, explosive workout. You get everything fit in an hour," said Melanie Reed of Laguna Niguel.