I just spent five and a half months bicycling 7600 miles across the United States -- AMA!
I started bicycling from Bar Harbor, ME on April 23 and just got to San Francisco, CA this last Tuesday. I rode 7600 miles over 24 states, met all sorts of people, learned a ton about life/myself, and had a generally great time.
I started out to see what I was capable of--I had spent the last couple years losing 80lbs, overcoming depression and alcoholism, and generally pulling myself out of a pretty bad place. If I can do it, you can do it.
My Proof: Here's my travel blog, though I'm still working on the last few entries up to and including the "finish line": www.whereswinslow.com
If you're interested in doing something like this yourself, check out:
www.adventurecycling.org -- A great organization that sells amazing maps and route information. The TransAmerica Trail route they have is kind of the Appalachian Trail of cross country bicycling.
www.crazyguyonabike.org -- Tons of travel blogs from people all over the place. Penny farthing rides around the world...Trips that are still going on after 5 years...Or just a nice journal from someone riding in your area. It inspired me every day while I worked a cubicle farm job to save money.