I've been putting my daily ride information into an Excel spreadsheet for 10 years. Distance, average speed, bike I rode and then notes, where I went, who I rode with, the weather, for cold weather rides, I might note what clothes I wore, Average HR, Maximum HR, how I felt, did I enjoy the ride, did I plan on 50 miles and cut it short to 30?, notes on my various orthopedic complaints, notes about bicycle maintenance (i.e., "new rear tire") and whatever else I care to jot down. I felt good because I climbed the hills better than the others today. Or not.

I look back at it all the time for everything from remembering how fast I did a particular route 3 years ago to when i started noting a new pain in my heel, when I was or wan't taking NSAIDs, to the name of that guy who came along on that ride, etc.

Lots of people keep diaries or journals about their lives. Mine just happens to be all about my cycling life.