"Take care of yourself" / Selfcare - it's so vague, how does one do that??

I don't find really good explanations. All the things that show up on Google seem either so basic, you'd die if you didn't do them (food, sleep, liquid). Or so fancy (spa day and so on) or just so vague. Here's the first google result I get:

• Do a relaxing activity. ...
• Set goals and priorities. ...
• Practice gratitude. ...
• Focus on positivity. ...
• Stay connected. ...

And while gratitude and positivity are still kind of clear, the others are more or less super vague and they also make me think that they're just so detached and have nothing really to do with taking care of myself.
I mean maybe relaxing activities help, but they seem more stressful. As does staying connected. Or setting goals and priorities. There are not the type of things I am capable of doing to recover when I have a bad day or a meltdown or shutdown or run out of spoons. These are things for good days.

How do I take care of myself on bad days, to feel better again and recover, other than eating, drinking and sleeping and trying to practice hygiene?