I find this to be an intriguing idea, especially having had a lot of difficulty maintaining any kind of exercise regime in the past. Can you explain in more detail the kind of bookkeeping required, and also the effects you personally feel as a result of having developed the habit of exercising?

I am not the best person to ask. I've always been a health nut and I've spent years at a time training for marathons (ie. addicted to running), doing various martial arts and soccer. What I was doing was reforming a running habit after letting it slide in favour of being a gym junkie with some mates. Once I got used to associating exercise with socialization it was amazingly hard to get back into the solo running habit. This is even though I know the time alone in a state of flow, with all the hormones associated with intense cardio, is extremely important to me. It is great for stress relief and gives my brain a chance to think things through, solve problem and occasionally write code in my head.