If you aren't already doing it...
You need to learn to say the word "No."
Say it often.
Say it unapologetically.
Setting clear boundaries for yourself and others is one of the best things you can do.
Not only for your sanity...
But also for your progression in life.
There's nothing wrong with saying "no."
You aren't being selfish.
You aren't letting people down.
You aren't being a dick.
You're being mindful of your own peace and productivity, both of which are extremely important elements of building the life you truly want.
So do yourself a favor...
Learn to say "No."
You'll spare yourself a lot of anger and frustration as a result.