I also ride mostly by myself ,and like Starfish I use Charity rides as motivation. If I don't ride in the morning on the weekends I wont ride. I just get up ,and put on my stuff ,and go. I always feel better about myself after I've done it. If you do it about the same time every day it will become a habit. Sometimes I look at other runners/ riders as motivation. Once you get out there it will become easier.