If you can't find the motivation to do exercise just put on some music (I like it loud) and just move to it. Usually my "moves" are cross between a power step, jog, and jump, swing my arms a bit and move my head to the music. (Make sure there's no one watching!) You will be surprised how much fun you'll have and how the time will fly. It's not a substitute for a workout routine, but getting your legs moving is always better than the couch!
I can always build up enough of a sweat and heart-rate to at least be as good as a good power-walk. Consider it your own Zumba, without learning any moves - particularly if you want your own beats! (not a fan of the Latin Zumba styles)