I'm a huge fan of Turbo Jam, Tae Bo and 30 Day Shred, all at home DVD workouts. I switch them up to throw variety into my workouts (although I have been slacking a lot lately). Don't forget you can boost your calorie burn by just adding little stuff to every day life. I use the bathroom at the other end of my school, walk papers down to my students rather than email and make as many trips up and down the stairs as I can. I make up reasons to walk, whether it's just to go ask someone a question who I could have emailed or check in with people at the other end of the building.