Early in my career, I routinely worked 50 hrs/wk. Not on purpose; I just preferred to get to the office early to avoid the morning rush hour, and I often stayed

Early in my career, I routinely worked 50 hrs/wk. Not on purpose; I just preferred to get to the office early to avoid the morning rush hour, and I often stayed around late to get a drink with co-workers after work. I was always productive, and it wasn't until years later that I realized that 50 hrs/wk adds up to an extra 3 months/yr. Same job, about six years into it, a major project came up that I had staked my reputation on. For almost six months, I was working 80-100 hrs/wk. It destroyed me. My metabolism shut down, my thyroid was damaged. My body temperature dropped from 98.6F to 97F, and overnight while I slept it dropped to 96F and I had trouble waking up in the mornings. I found out later that if it had dropped any lower than that, my body would not have been able to warm itself back up. It took about a decade for my temperature to return to normal, but I still need thyroid medication. And my ability to work long hours has never returned; it's a good thing productivity continues to increase with experience. I work a lot smarter now. EDIT: the project was a success, at least. My boss was awarded employee of the year, but I was awarded second employee of the year, which was the only time they did that. I also got a little engraved glass plaque, the kind that comes from a corporate gifts catalog. Maybe a $50 gift card too. So worth destroying my metabolism for over a decade.