I just factor it in to my plans. My "spoon limit" per day is pathetically low - I'm not able to work at all and even a shower requires a nap afterwards.
If I plan a fun outing like the cinema or a concert or a family party then I make sure I have no appointments or other tasks required for a couple of days afterwards so I can just sleep as much as I need and chill out with a simple video game.
I visit my family every Sunday so never plan anything on Mondays as that's recovery day.
Luckily my doctor is quite on the ball when it comes to pain relief and I get enough morphine to cover a couple of days out + my weekend visits so that the pain doesn't stop me from being social. It's just the tiredness I have to power through.
I refuse to make myself feel awful for something I won't actually enjoy though. If I'm invited to an event I'm not interested in then I'll turn it down. Feeling that the pain was "worth it" makes a big difference to my mood on the bad days and helps me get through it.
EDIT: it took me a long time to learn my limits and I made a lot of mistakes along the way, treat them as new data points to work with and don't beat yourself up. It's mostly guesswork to start with and there is no point punishing yourself for not being able to guess the unknowable. I've been dealing with fibromyalgia since I was 17 and I'm now mid thirties so I've had almost 20 years to reframe things.