I mostly ride alone, too...and I have weight to lose, too. For me, it is all about having a goal, and having support.

I am motivated by having a goal ride to train for, and by telling everyone so that I can't back out when I feel like it. With charity rides often having very short options in addition to their long rides, people of all levels can find good goal events.

Also, I recently had the great good fortune to find an online training buddy...nothing formal, but we swap emails, and I find it extremely helpful to know that there is someone out there I need to report my efforts to. These forums are wonderful for finding encouragement and support.

Finally, I find that when I have support in all areas of my life (whether it is through a prayer group, al anon, a counselor, what-have-you), I do better about taking care of myself through biking.

Hope this helps!