One would think that a programmer/statistician could work forever, but sitting in a chair and typing all day long can take a toll on your body. Worse than that though, you begin to lose it mentally. In my case, I can still get my work done, but it's more difficult to focus and concentrate. Getting back into teaching the last few years has helped give me a break from sitting in the chair all day. It also does not take as much concentration and working with younger people is energizing. Doing both does add up to a lot of hours though! I stll think I can make it until 70 if our university does not get destroyed by budget cuts.