I go through this too, sometimes. I have lots of exercise videos and many times it's just easier and faster to just workout at home, rather than get all the gear together (clothes, shoes, helmet, water, etc). Sometimes it's physical laziness, sometimes psychological (for me). I don't know how often you ride, but maybe you just need a break from it?

When I'm in one of these slumps, I like to ride my bike to the store, or library - anyplace within a few miles so I won't be gone for long, and I actually have a purpose. I don't need the gear - I just go. Sometimes that little taste perks me up and then sometimes I'll ride around the block a few more times just for fun. I hope you feel better soon!