Doesn't it feel like every person you know raves about their workouts at SoulCycle? Or maybe all your friends are really into barre class instead. Whatever it is right now, it will probably be something different by summer. Yep, there's always a new way to whip you into shape.And it turns out, when it comes to working out, modern humans have pretty much always craved variety. In fact, fitness trends and workout crazes have been around for thousands of years, dating back to Ancient Greece . But for women, particularly women in the U.S. and Britain, fitness became a priority at the turn of the 20th century . As researchers began to focus on the effects of exercise on the human body — especially the female form — new workout trends were developed.And over the years, we've been given every manner of fitness craze: From dumbbells and stretches in bloomers to high-cut bodysuits and neon spandex for Jazzercise. Not all fitness trends are crazy or funny or require outrageous outfits. But so many of them have — and therein lies a lot of the fun.From Buns of Steel videos, to the ThighMaster, to the magic of the Trim Twist, click ahead for some of the craziest, funniest, weirdest, and all around best workout trends from the past 100 years. Who knows, maybe you'll want to try one this #tbt.