Do you know what my favorite word is? No? That's right! Huge amounts of time, money, and emotional energy are wasted because some people can't or won't just say NO when they really should.
NO is critical to good time management and avoiding spending your valuable time on Other Peoples Problems. It's not a free pass to avoid what you ought to do, but it is the best way to decline doing what just isn't in your wheelhouse.
I know, it sounds harsh and makes you feel like a meanie, but when you agree to something you really shouldn't you're just setting everybody up for disappointment at a later date. Let's get the disappointment over with now and move on to getting something valuable done.