I hate working in an environment where I can't choose my own pace. I work to the limit of the law; 14 hours a day, 70 hours a week and try to put the maximum productivity into those hours. I don't take breaks because I find it easier to just work straight through. There is enough variety in my job that I don't get bored.
Luckily, I answer only to myself and have nobody answering to me. I would not make a good boss, as I would expect the same performance as I try to give.