Another Edit: some observations are there shouldn't be any jobs out there that require people to work that long hours, it's inhuman.
Well there are people out there who need that much money and will work two jobs for it. There are jobs there that the sheer amount of work will just consume your day-to-day waking hours, ask startup CEOs, ask all the passionate entrepreneurs, ask full-time researchers... And there are jobs require people constantly communicate with people in three continents and 10 different countries and cover timezones that has 16 hours difference. And there are jobs you have to be constantly alerted because 24 / 7 there are other peoples' lives / family / happiness / money depend on it. For the people who work in these professions and love what they do, don't you think there have to be ways for them to properly do their jobs and don't get burnt out or less burnt out if possible? That's why I answered this question.
Edit: this is not for mothers or fathers that like to spend quality time with their kids to follow. I think if you plan to take your kids to school on weekdays and bring them to the zoo on weekends, below will NOT work. At the end of the day, this is about priority of your life, if you choose to spend more of your time working than others, it's a completely independent, individual life choice that your are making.
I have worked 80 - 100 hours for the past three years and am likely to continue to work at least 70 hours or more in my next gig.
So in short, get your priorities straight.
1. Calendarize your loved ones, and make your apologies now if you are getting into it. Really calendarize. CALL YOUR MOM TIME AND LUNCH WITH YOUR BOYFRIEND TIME AND COFFEE WITH YOUR FRIEND TIME, etc., in advance. Otherwise meetings and conferences will fill up your calendar and perhaps you also travel a ton, then you will lose them. Of course, even if you plan ahead, last minute cancellation happens. Just make sure they are informed as early as possible and apologize. Sincerely. Don't take anyone sticking around for granted.
2. Prioritize your fitness and well-being. I still go to the gym or hike (I live in a city that has 30+ amazing trails) at least 3 times a week and I try to eat healthily. At the end of the day, if I work late hours in the office and still eat pizza and fries every day, I probably would have died on my desk in one of those all-nighters...
3. Recharge during your vacations. Don't feel guilty when you apply for vacations. What? Why would people feel guilty for applying for vacations? Busy people in busy teams do feel guilty. But you'll need it. Go somewhere in a different timezone or somewhat different from your working environment. Beach, mountains, deserts, whatever. I hiked a lot of mountains during my leaves; it takes the heat off and it feels as challenging as my job is (huh, you know how stressful my job must be...) and the best of all, it feels sooooooo good when you are standing on top of a mountain. Of course I took beach holidays, ski trips and family city trips too like all normal people ;) I love aquariums!! In a lot of big cities!
4. Don't get addicted to caffeine. May sound counterintuitive, but this is the best advice l've been advocating to all my peers and even my bosses. Don't drink that much espresso, coke zero and especially red bulls WHEN you are TOTALLY OK to function / focus. Consciously reduce your caffeine intake and try to fight the fatigue a little bit if you are already so hooked. So that when you are really really tired, one of these things will actually be effective (like after you work on something for 24 hours straight). I drink no caffeinated drinks now during a normal day. I drink juices, decaf (occasionally if I really miss a latte) and sometimes green tea if I'm really having a tough night.
5. Would be good if you still have sex. If you can keep a partner. That you love. Don't just keep someone around because you want a cuddle and sometimes breakfast in your bed. Not fair. Find someone you like to spend your limited time with and laugh together.
6. A lot of communication with your team and your boss. It would feel the worst if something that takes a whole week of your time is actually not what your team / boss wanted. Communicate communicate communicate. I can't stress this point more. You don't have that much time to waste.
Hope it's helpful if you really choose to work in such professions that require long hours. But really choose wisely. Stuck in a job that you absolutely hate that occupies 80 hours + of your week, I can't think of a better torture.