When I'm feeling low I turn to standing poses and hip openers. If my 'feeling low' is also full of negative brain chatter (symptom of my dysthymia), I also hit the treadmill for about half an hour and have eggs, turkey, whole grains or potatoes in the next several meals; and make sure I'm giving myself enough time to sleep, and to relax before I sleep.
Good luck; I'm willing to chat more about this if you'd like (on forum or via PM.)