All you guys who work 10-12 hour days, I'd be interested to know how the rest of your day breaks down.
I'll use my case as an example. I need 8 hours of sleep. I know some people get away with 5 or 6 - good for you. I've tried less but I cannot function properly on less than 8, it's just the way I'm built (and I don't rely on caffine!). So that leaves 16 waking hours. I need 45 minutes to shower, have breakfast, prepare lunch etc. which is probably quicker than most. The commute to work is around 35 minutes each way (lucky I don't live in London where the average commute is 55 mins each way I believe).
That leaves about 14 hours. I work 7.5 hours but at the office for 8.5 including lunch. Some days I go to the gym which luckily is in the building but for most people this is an after work activity. Let's assume I go after work instead with 5.5 hours remaining. Getting to the gym (or other sporting activity place), doing the workout and showering would take 1.5 hours if I'm quick.
I'll switch to 2nd person narrative. You get home with 4 hours left before you have to sleep. You still have to prepare a meal, perhaps do some laundry, cleaning or other chore. So you have 2.5 hours left to enjoy your evening (or 4 hours if you skipped the gym) with your wife, kids or internet porn.
So what happens when you suddenly start working 10 hour days? No time left in the evening to live your life. 12 hours days? Kiss goodbye to your sleep time. Then you wake up in a bad mood, lethargic and unable to perform your job properly.
In conclusion life for most people, especially those with a family, is a careful balance so no amount of "having a sense of duty for your work" should not take precedence over anything else in life. 8 hours is an acceptable amount of time for one to dedicate to their working day.