I think Machka's recommendations have a lot of merit. My wife and I ride all year long. She trains pretty hard for the spring triathlon season and we just carry it forward into getting ready for our tours. We generally get a good 800-1000 miles on our touring bikes in the 3 months preceeding our trips. It isn't "training"- we just like riding together. We sprint to the road signs and play on the hills. It is just having fun on bikes. She has the polka dot jersey right now. A couple of years ago we averaged 50 miles a day, fully loaded, for 74 days. I would not have been able to do that without preparation. We are both over 50, and one of us is well over 50. At 21 years old recovery should not be a problem, but as we get older it becomes more of an issue. I think training allows faster recovery, and builds a reserve for those days when you have to dig a little deeper.

Have a great ride!