I wish I had some better advice for you. I used to be really big on various charity races, but the constant fund raising wore me out. I will still fundraise and do races...I will be at the Bike MS as well this year, but I don't feel guilty because I am not as motivated or enthusiastic. I know that going out and supporting is half the battle, because promoting awareness is just as important.

I had a different problem but my solution might help. In my case I had trouble motivating sponsors for my second year of doing a 600 km charity ride. I think many of the folks I knew just thought "Well, 600 km isn't all that crazy a thing for him." And so the next year I pledged to tack on 400-1600 kilometres to the end of the ride based on how much over the minimum I got to.

It worked well and I made my record, but what I also got, which you might find motivating, is an extra 400 km bicycle tour through Quebec, meeting interesting couchsurfing hosts - a very memorable trip.

The next year I did something different - encouraging folks to perform acts of kindness in lieu of pledges (allowing anyone to pledge regardless of income). My son rode with me that time and we went even further.

Sadly since then, I can't seem to motivate people to pledge money or acts of kindness so now I just tour and give my time and money to the organizations instead of riding.

If the ride itself isn't motivating, would another ride be more interesting? Unless you're really benefiting from the MS Society promotions, why not create your own ride and use a site that collects pledges for you (in Canada we have canadahelps.com, for example) In that way you could raise the money but do your own trip. ("Saigon to Singapore for MS") that has more interest. I've always thought that if I were to ever figure out how to be successful at fundraising again, I'd do something like that instead of joining an organized ride.