Here's an exercise tip for those who want to exercise but have every excuse not to (valid or not). Stand on your tippy toes during your commute and to to go as long as you can stand before coming back down on your entire foot. Use the hand straps to stabilize but don't hold your weight in them. I usually go 5 stops then rest for a stop and repeat. This works really well for long commutes and jerky subway lines like Line 1.