I stopped working while I was still young enough to do things I found interesting. Some mornings my bones disagree, but I have to say it has worked out pretty well. A couple of years after I graduated from engineering school, the owner of the company I was working for asked what I wanted to accomplish in my career. I said that I wanted to save enough to stop working for long enough to build a house. So, when I retired I rode my bikes a couple thousand kilometers in the first three weeks, played some guitar, raised some money for cancer research and then went to do some building.