I agree that developers should not try to work more than 40 hours per week on a regular basis. But when I was younger, I went for years working around 16 hours

I agree that developers should not try to work more than 40 hours per week on a regular basis. But when I was younger, I went for years working around 16 hours per day, 7 days per week and everybody thought that I was a rockstar genius. But it was not all mental work. I probably spent about 8 hours a day on software development and then I wehnt home and worked another 8 hours in my half acre of gardens, 3 acre asparagus field or shoveling the daily snowfall of 6 inches or so, off my 100 yard driveway. Not to mention sawing and splitting a few cords of firewood to heat the house, cutting Christmas trees to sell. The physical work was energizing after a day spent writing software, and the mental work was energizing after all the physical labor that I had done the day before. I'm not saying that the physical labor made me more productive at developing software, although that may be true. But I think that when people count hours and then try to use that to prove a point, they forget to classify what is being done in those hours. Case in point. When I have a tough coding problem, I don't slog away at it for extra hours. I go sit in a different chair, stare out the window, look at the cloud shapes, then close my eyes and think of absurd ways to solve the problem. Now if I would include that time in my count of hours per day and tell you that I can regularly put in a 10 hour day, you would be misled. The total hours are not as important as what you do with those hours. If you are going to play on the net for 20 hours a week, then yeah, you may need to put in a full 60 hours. Or you could stop goofing around and do your work. Pay attention to your productivity. Split your day into chunks, take your coffee and lunch breaks. I used to join the smokers on their smoke breaks even though I didn't smoke because it got me out of the chair, moving around, and I got to stand in the fresh air and sunshine (upwind of course). And I almost always go for a walk at lunchtime. This is not a waste of time. These pauses are essential for you to get your maximum mental effort. Sure, sometimes you get stuck into a problems and go for hours without leaving the chair. Even if you are 50 you can do that once in a while if you eat healthy (read Joel Fuhrman), but the key here is "once in a while". Once in a while you can pull out all the stops, but like heroin, it does not get better by doubling the dose. Buddha had it right when he said (and I paraphrase him) "All things in Moderation". It takes great discipline, but discipline is what software developers need to cultivate in themselves.