Music will set you free, and not just for your workout!
Many people have "workout playlists" and such, but what about "don't get home from work & head straight for the couch playlists". Keep your music player handy and crank up the tunes before you have a chance to sit down.
And the best part about it is, it doesn't have to be all the upbeat techno crap you call "motivation" music. Make a list of ALL the songs you love, put it on shuffle and see how much easier it is to keep moving, instead of sitting down and vegging out!