I guess it depends on where you are down the road, and how much you take on, in terms of work/life balance. I'm not sure I have it, but I'm a lot more careful about burn out than I used to be.
I'm up at 6.15am in order to get ready and tidy our flat, and dropped at the bus station to take the bus at 7.20am. I have around a 20 min trip to work (or 40 if I miss my normal bus), this allows me to catch up on my UX reading and different feeds. I then work from 8am - 4.30am, and take the bus home again, allowing me more reading time.
I'm a little naughty, I also tend to eat lunch at my desk and catch up on news, or complete some personal project work, unless I'm doing yoga/pilates, so I don't give myself an actual break.
Getting home around 5.30pm, I make dinner for my partner and I, then we either work on individual projects, go to the gym, boardgames or Karate classes. Due to my introverted tendencies, I tend to get very tired if I'm out and about a lot after work, so I try and have a minimum of 2 nights where I stay at home to recharge.
Like Hawk, I try and have one day in the weekend where I'm not doing work of any kind, usually the Sunday, in order to recharge by Monday. This gives me Saturday to work on projects, interspersed with tennis.
So I think the thing that helps me the most is learning how much I can handle, and saying no to things that I can't so that I don't burn out, or become so stressed my productivity suffers. I also think that the physical activity gives a nice change of pace and helps to burn off any frustrations felt throughout the week. Setting a time that you do stop working and are in bed by is also good, because it sets a standard that your health, and being recharged and more focused is higher priority than staying up slogging away.