This I'm sure resonates with a lot of people, but unfortunately it's sometimes hard to cut out the takers: when they're part of your close friend circle or worse, your family.
I was having trouble with this once and a wiser friend told me it's perfectly acceptable to say "I've decided x".
So I tried it out, and it seems to work. Some people are much more talented at the right level of response.
Oh, and also: https://xkcd.com/2346/