I do exercise but it's usually a 20 minute walk at lunch and a 3 mile walk in the evenings. I never get enough sleep, so exercise in the mornings is excruciating, and between working 9-10 hours days and thesis+other stuff at night, I don't feel like I can carve out more time than I do. Ideally I'd like to have both a 4-5 mile walk and strength training every day, with yoga and qi gong mixed in.