I second everyone else on the importance of sleep! I can't tell you how many times a good night's sleep (or even just a nap) reset my mood or lessened the stress I was feeling. If I doesn't (or sleep eludes me), that's when I know something is out of whack.

My life is generally too chaotic to have a set schedule or routine, so what I do instead is set what I call totems throughout the day. Things I can do that are set aside for me and me only that I can do on a regular basis. Some totems I've had are having dinner after work on Fridays, seeing a movie in the cinema, having breakfast (or lunch) and reading a book. Things to keep me from feeling adrift.