Paperwork
One of the biggest things that helped me was rearranging where I completed certain tasks. Specifically, I tried to get as much grading as possible completed at school, and saved lesson planning and preparation for after grading or at-home work. For one, who enjoys grading? Forcing myself to do that first helped quite a bit - as they say, when you have a bucket of frogs to swallow, swallow the biggest one first and the rest go down nice and smooth. Two, that meant schlepping a whole lot less stuff back and forth between home and work (and let's be honest, how often does that grading bag go unopened in your home?). Three, you can do a lot of the lesson pre-planning in your head while making dinner, vacuuming, folding clothes, etc, rather than just staring at a screen at work or rummaging through TPT hoping for inspiration.
Nightly Routine
A scrambled morning leads to an off-kilter day. One way to make your mornings go much smoother is to prepare as much the night before as possible. Before turning in I made sure my clothes for the next day were laid out, lunch was packed, school bag was packed, breakfast dishes were out, running clothes were laid out if I planned to run in the morning (or I just slept in them - you get out the door much faster that way!), etc. That way if everything went according to plan, my morning was easy-peasy. If weird things came up (power outage, dropped glass - happened twice my last year of teaching - that had to be cleaned up, pets escaping into the garage, whatever) I was much better equipped to handle them and didn't get set as far behind. This goes even better if you can spend time on Sunday doing extra meal prep!
Exercise
This is one of those things that we all know is super important but we tend to relegate it to the "if I have time" category. Probably the number one benefit I derive from exercise is better sleep - we all need better sleep! I'm also a morning runner, so it's a great start to the day: I get those endorphins going and feel like I've already accomplished something first thing. And it just makes me feel better about myself, which is going to make me a more pleasant person. I've also heard some rumors that it does something good for your heart, lungs, metabolism...
Social Life
Who has time for a social life during the school year - at least one that doesn't involve basketball games, concession stands, or school dances? For me, I made Friday nights a "night off" - no grading, no lesson prep, no researching... just an evening with the husband. Then I'd try to get as much accomplished on Saturday as I could, to free up my Sundays for relaxation (ugh, Sunday night work is the WORST!). My closest girlfriends live in Chicago, about an hour's drive for me. A few years ago I made a commitment to myself to get up there once a month. It didn't work out every single month, but it made a huge difference in my stress level and overall happiness meter when I was able to spend at least a few hours up there for brunch and girl talk.
Looking Forward to...
Tying in with the last one, I found it's a huge help to plan things to look forward to. They don't have to be big events - even planning a coffee date with a friend a couple of weeks out is enough. By setting plans it forces you to break out of your teacher persona, forces you to leave the piles behind. And, when you're feeling overwhelmed by all that you have to do, it gives you a bright spot in the near future to look ahead to.