The cemeteries are filled with people who thought the world couldn’t get along without them
— Multiple sources, original author unclear
As you start the new year, please take a moment to remind yourself that whatever you do and how good you are at it, your employer (and society as a whole) will continue to function with or without you. This means that you should never be ashamed or feel anxious about taking “off” time, and by that I mean all of the time allowed by your employer every year. Not only will you get more productive overall, your friends and family will thank you for it. I certainly expect all of my students and postdocs to take time off.
Second, make space in (busy) your agenda for yourself. Yes, that is right, do schedule time with yourself as you would do for any meetings, colleagues or students. Call it whatever you need: weekly brainstorming, weekly review, … More importantly consider it as important as any other tasks with a strict deadline. Bearing major health/family issue, you should never skip it. By trial and error, I found that the optimal seems to be 90 min/week on Friday afternoon.
Finally, if for any reason you end up working well over 60h/week (you know because research can also be a hobby not just a job!), not occasionally because of a deadline but rather consistently all the time, all year around, you are most likely spending a good fraction of that time at simply being busy. Being busy is very easy but that does not mean it is the best use of your time or a sign of creativity. Take the time to do something else, your overall creative, high-quality scientific productivity might even increase significantly.