At one of my previous jobs, I took Monday off as a flexday, and that was great. You'd start the week a little behind on Tuesday and by the time you were caught up, it was the end of the day and you were practically already in the middle of the week! It made the work week fly by.
I don't have that option at my current job, at the moment. So I take long lunch hours on Tues and Thurs to go biking at Hains Point. Anytime I start getting depressed on a Monday (or Wednesday), I just think, well, at least I'll get a good ride in tomorrow. That helps quite a bit.