The various ways to stay in shape go back further than your parents' worn out copy of Jane Fonda's instructional VHS tape.

In this new video, we get a glimpse at 100 years of fitness crazes. It starts out harmlessly enough with simple stretched in the 1910s before moving through the hula hoop fad of the '50s and continuing with Jazzercise, the Fonda-embraced aerobics, Tae Bo and today's Zumba.

A lot of these are fun to laugh at today, but, remember, a lot of people once swore by them. So, before you head of to Zumba class, just think that in another 20 years you're going to look back and shake your head in disbelief right as you get set to call up your personal hologram trainer to focus on those glutes and firm your core.