Yes, I most certainly do. Right now I'm working 18-hour days, seven days a week and have been for the past six months. If I'm lucky, I can sleep when I'm done working -- if I'm not, baby decides she's going to stay up for a while. Thankfully, I am making huge advancements on my goals, and should be able to revert to a more sane schedule within the next few months. This is not something I desire to keep up, and as soon as my training program is launched then I can calm down -- I just need the darn thing out and hopefully the first round filled before mid-November.
As far as how hard I work -- it's not physically difficult, but very mentally strenuous. I spend my time very focused on my work so a lot gets done, but not much respite for the brain. Lunch over -- back to it! :D