I agree with what break these cuffs said. My definition is anything you do to keep yourself mentally, physically, or emotionally well. Athletes put marks on their calendar of when to practice and when to rest, and keep up with physicals. An office worker might take a long hike in the woods every other week or so to connect back to nature.
I'd say putting make up on yourself can occasionally be self care: if you use it occasionally to feel fancy or confident, that's fine. If you used to put on make up before you're married but now you don't and want to do it again on occasion to feel attractive to yourself, then do it. It is always how you use it, whether it is a crutch or just a signal for your brain to relax and enjoy itself. A glass of wine a week for fun or celebrating the end of a hard week is different from getting shitfaced every night so you don't have to remember your life choices, everything in moderation and all that.
But what if me woman???? What if I get woman and she got me to care for her??? What we do then???
No, but I really want to now!
You're in the beauty parlor dipshit, it's soy all the way down.
Even then, self care involves hygiene, treating your body right with diet & proper exercise, and challenging yourself without burning the candle at both ends. Chaddites become Chads because they learn how to take care of themselves, not because they indulge in binge eating or refuse to take showers. Even getting hurt and then properly nursing yourself back to health because you're focused on keeping your body well for yourself is self care.
Please tell me you shower for yourself, at least.