Considering you can be an otaku regarding just about any hobby, it would be unfair to generalize all otaku as unfit or not interested in exercise. That said, it's probably not unfair conjecture to say that the overlapping area of a Venn diagram between "otaku who own a body pillow" and "otaku who love going to the gym" might not be the most crowded ever. Regardless of nerdy stereotypes, however, at least one Japanese Twitter user has found a method to incorporate your body pillow into your home workouts. @torimamo81kai's video demonstrates how to kiss your waifu while making some gains.

Another video demonstrates a playful tradition between lovers on the official holiday of one of Japan's favorite snacks, Pocky. On Pocky Day (November 11th, as 11/11 looks like Pocky sticks lined up), some couples play the "Pocky Game", which is basically two people nibbling on a shared Pocky stick until they kiss. Here it is demonstrated by two Guinea Pigs. The video below shows that you use it to hit your macros as you work out and spend time with your body pillow.

While clearly, (well, likely) posted in jest, it's at least an update over this technique.