Saying no is good for my mental health.
I stopped visiting in-laws about 3 years ago, but don't prevent DH going and taking DS (they aren't abusive, just a bit cunty , pardon my Latin). It's AMAZING not going!
We have good friends who are social butterflies and we say no to about 1/2 or 1/3 of their invites as although we love them dearly, we don't get an awful lot of free time as a family. We're thinking of camping with them this year, do it's not a big deal to decline a few things.
Once I hit about 32/33yo, I'd reflect on a night out, or whatever, and think 'good god that was Ballache City, not doing that again', or the contrary.
Occasionally I'll think 'oh, not that again?' but still go so DS can play with other kids, or just go keep up appearances, but to feel in control of that compromise is empowering.
I sound like complete bitch with no friends, but I'm not, honest! 