I'll admit it, I'm the obsessive type. Once I get motivated to do something I tend to go full steam ahead and although this is a little too much of a train metaphor for my liking, I get tunnel vision and it becomes hard for me to see where and when I should brake. I'll work and work and work and then all of a sudden I hit a wall and it's called exhaustion.
Use others as an excuse.
If you feel fine allocating a day or a few days for a solid break then by all means go ahead and do that for yourself, but if that would make you feel guilty or if that's just not practical for you then a great way to get in a little breathing space is to make plans with friends or family. A coffee catch up, a brunch date or seeing a movie with someone- all of these things offer opportunities to take a mental break from everything and because all of these things involve another person, no matter how busy you are you can always use the excuse "they're relying on me to not flake out on them..." to ensure you actually take that break and go!
Delegate things to the 'future' you and prioritise your current self.
Whenever I'm feeling really stressed, something I like to do is to refer to myself in the third person (apparently that's one of the first signs of being a psychopath?!). What I mean by that is if it's a Friday night and I'm tired with a huge list of things I need to get done in the next few days, instead of worrying about everything to come I'll prioritise the 'current' version of myself and just focus on the present moment by saying to myself "Saturday morning's version of Julia can handle that." I know this may sound like a weird tactic but it actually keeps me grounded in the moment and it's really helpful in terms of making sure I don't run myself into the ground. I'll admit, sometimes I give 'tomorrow's version' of me a little too much to handle but it's all worth it if today's version is well rested and happy.
Go hard or go home.
Book a holiday. It's an indulgent, treat yo'self (Parks and Rec fans unite), sometimes impulsive decision but booking yourself a holiday is one of the greatest things you can do for yourself in my opinion. Book something across the world or an hour away from home, just go somewhere with the pure intention of relaxing and taking a vacation from your 'real' life. Your responsibilities will be there when you get home, so enjoy yourself.
Are you a workaholic? Do you have trouble with giving yourself breaks?