From the ThighMaster to goat yoga, the fitness industry has seen some surprising fads in recent years. However, people have been using unconventional ways to get fit and look their best for decades.

Vintage athleticwear is surging in popularity.

For many people, dance feels more like play than exercise, which helps to explain its enduring appeal as a workout. What began as “aerobic dancing” in the 1970s has evolved with exercise science (and ...