I've had a problem with motivation before. I have a tiring 40+ hour work week, a 60 mile commute(1 way), and am taking 14 units in school. On the days that I have time to ride, I usually feel so exhausted I use the time to catch up on sleep. My motivation is driving by others and seeing how happy they are, logging online and hearing other peoples adventures, and seeing how sad my bike looks in the garage.

My big thing has been to not force myself to ride. I know the way I think, and if I force myself to do it, I will just come to resent it, no matter how much I actually do enjoy it. I just try to make it as easy as possible for me to ride, even if only for a few hours. Keeping my bike ready to grab and go, tires inflated, clothes/shoes easily accessible, etc.