Good luck Jeannette!
Susie I did a 100k a couple of weeks ago with my DH. First it was going to be 50 miles...then I noticed there was no 50 mile-only 50k and 100k (and 100 miles, but I'm not THAT crazy!) So I agreed to do the 100k. It was challenging, but satisfying. The snacks and post-ride pizza, subs and other food definitely helped my outlook.
Hope your ride is great, too!
Maura