Yeah, anything repetitive will make me mentally claustrophobic. I can do a 30 mile bike ride as long as the scenery changes; if the terrain is flat and I keep going straight and see the same type of shyt, I'm ready to quit after 5 miles. But playing games with my mind, like trying to beat time limit goals and shyt definitely keeps my mind stimulated. I've been doing 200-250 pushups at the end of every workout, in sets of 30, 35, or 40. In order for it to work I have to do each set in a different location in the gym, starting on the 3rd floor and going down, then a couple sets in the steam room, a couple in the locker room, one in the bathroom. And I keep the time running, try to set a new personal record each time. Otherwise I'd get bored after 3 sets.