I’ve always found it odd when I hear people say this. I’m never quite sure how I’m supposed to take it. I live alone. I have like zero responsibilities outside of work. So in that regard, every single day I do “something nice” for myself. I get to eat whatever I want, watch whatever I want on TV, etc.
One “argument” I’ve heard that this is instead supposed to mean to like exercise or something, but I exercise is very unpleasant to me. I committed to consistent running for over a year and never enjoyed it lol. I feel similarly about all forms of exercise.
I dunno. What am I missing here? Is telling people to do something nice for themselves reserved for people with heavy responsibilities like children and such? Because I don’t understand why people would tell me to do that to myself or how I am supposed to apply that. Existing with high freedom and low responsibilities seems pretty nice to myself so I don’t get it.
Am I just dumb lol?

People say that because they want to be nice. But it’s hard for people to understand when someone thinks and feels significantly differently than they do.
So it might be useful to think of it as, “this person hopes I have a positive experience.” They say it in a way that makes sense to them, and they don’t realize that you think of things differently.
So when they say “do something you like,” think of it as them saying “I hope you do something that makes you feel good.” You may not “like” things the way most people do, but you can still feel good about things - even if it’s an intellectual “this is positive,” as opposed to an emotional “I’m doing something that makes me feel happy.”