There's also three different instances where your little mutant can lift dumbbells. I found them both cute and amusing. And I hope in a future update that we can play this animation whenever we want, like in a player home or something. Along side that are these weight bench instances, the shot here is of me completing the last bench of three, after I previously done all three dumbbell ones, granting me the achievement you see there. (Max Gains)

All in all this is well worth it, because It can boost your strength considerably if you complete all the instances.

Youtube link to little clip
https://www.youtube.com/watch?v=w1U9hhLYRD4