Spoon Theory is a metaphor for describing certain limiting effects of a disability to those unfamiliar. It comes from this original post by writer Christine Miserandino which explains the basic idea. Here's its Wikipedia article.

It's called Spoon Theory

If you ever played a Zelda game, its how many "hearts" you have before you "faint". It's a metaphor about how much energy a person has, that can be usefully descriptive when discussing one's experiences with managing a chronic illness

Wanna shower? That'll cost ya a spoon. Maybe you've got eight of them, so how do you choose to use them? If you run out, you won't be able to cook yourself dinner, and there's no amount of "will power" that will help you

Use some medication to help you "push-through" because you're hungry? That'll cost ya a spoon on credit (when you wake up)

When it comes to disability — if you over-exert, it can cost you your entire next day while you rest and "restore hearts". So you have to learn how to manage your energy more conscientiously than you would if you didn't have "that disability"

The theory can help, not only to teach yourself how to manage your energy for everyday tasks, but also how to discuss the hurdles that your situation presents

In my own experience — it can be especially helpful in discussing how an "invisible illness" affects you... with family, friends, and sometimes acquaintances. And I find that to be kind, because it's easily digestible for the person who hasn't had those extremes of experiences

Regardless of my struggles, I'm very grateful for the amount of spoons I've been given