This is one of the most important if not THE most important exercise for building strength and mass. (fitnessandpower.com)
Personally, I believe pull ups are one of the most important exercises in a routine, and I recommend them to everyone.. (onnit.com)
A hamster wheel gives your hamster important exercise in its cage, while a hamster ball will allow you to give it similar activity outside the cage. (yourpethamster.com)