I used to have no boundaries. I was traveling every other week from Monday to Friday. When I was home, I was a mess -- waking up in the middle of the night, stressed, and working all hours. Three weeks before our wedding, my now-husband turned to me and said, "We are not going to last if this continues." This changed my life, kicking off a five-year (still continuing) experiment with creating boundaries to help me live a full life. Here is what I've learned so far:
This is up to you. No one is going to hand work-life balance to you. Companies will take as much as you will give them. You need to own your boundaries -- defining them, communicating them and being honest about how well you are sticking to them.
Understand how you work best. Make sure you are as effective as possible during working hours. When do you do your best work? Block that time on your calendar. I get 10x more done in an hour in the AM than one in the evening.
List your non-negotiables. For me, this was not having Monday night meetings (I was taking a class that I hated to miss), doing work after 9 PM (otherwise I couldn't sleep) and disconnecting between 6 and 8 PM for family. Whenever these are broken, I am stressed and unhappy.
Tell people. Communicate these non-negotiables with your manager. Frame it from their perspective: "I want to do the best work for the team. My strength is [xxx], and I've found when I am overworked and don't have these boundaries in place, [xxx] suffers."
Start today. Don't fall into the trap of saying, "I just need to power through the next month." Trust me, something else will come up. Do it.