We're taught at an early age to be agreeable and nice, and we tend to associate saying “yes” and making people happy as a good thing. But it’s not often that a person is taught at a young age that saying “no” is okay, you can still be agreeable and nice while saying “no,” and that saying “no” can be good for: a person’s mental health, opening up doors for something different or better, and healthy time management; just to name a few possibilities.
If you make a promise, you better be able to keep it. There’s nothing wrong with saying “no” up front when asked to do something for someone else.
It’s way more disappointing to deal with a broken promise rather than an honest “no” or “maybe, but not now.”