When the outside temperature plummets, squeezing in a cardio workout can feel like a chore. But now there's a solution: jumping jacks.

Don't worry, we're not talking about the boring standard jumping jacks you did in high school. We want you to try these 39 fun--but brutal!--variations created by BJ Gaddour, C.S.C.S., director of Men's Health StreamFIT. They'll get your muscles burning and your heart pumping in no time. You'll be anything but bored.

See them all in the video below.

This text will be replaced

And for more than 200 follow-along workout videos from Gaddour, check out Men's Health StreamFIT today!

Like us on facebook, follow us on twitter, and subscribe to our YouTube channel.

1962 Porsche Becomes BBQ Grill