Ladyfish - the MS150 is a fun ride, and if you think of it as successive 10 mile stints, you'll do fine. Around here, the MS Society hosts training rides for 2-3 months prior to the 150 (2-75 mile days), so if you do the training rides, you'll do fine. I figure if I can do it with asthma, anyone can. And if you crap out, there's always the friendly SAG folks to scrape you off the road.

You can do it! Do the training rides, with longer distances. And around mile 50 a dose of ibuprophen (motrin) helps . And another does when you finish. Drink water, eat snacks, have fun!