I feel the only way to be embarrassed is to have a bike that just collects dust.
No need to wait till spring to get ready. Unless there is snow or it's raining I'll be on the bike and then it will have to be snow that I can't get the bike to the canal.
I plan on doing a spring ride along the C&0 from Cumberland (mile 180) to near my house (mile 77) one day next spring; then from my daughters in Frostburg to here. I've done as many as 77 on the canal in one day. I'd like to work up to going from here to Pittsburg and back, about 500 miles, during a vacation week in July '12
As has been said, you want to ride for 40 miles then train at 50 or more. Makes 40 a breeze. Read what you can about keeping the rpm's up. I know it's helped me. I can get home after a long 50+ mile ride and don't even have to think about the stairs.
I recall when I started in July doing 10 miles was all I could do before needing a serious nap. Now I don't think twice of telling the wife I'll be back in 3 hrs which is about 50 miles. Given a good day I don't see a problem in riding a century a weekend - now isn't good since the time has shifted and it's hunting season. - way too many hobbies