A useful commitment has edges that both you and other people can recognize.

A commitment without edges cannot be kept, only endured. Saying you will help out sounds warm and leaves everyone guessing: how much, until when, and what counts as finished. The person relying on it builds larger plans than you intended, and you start feeling trapped by something you never quite agreed to.

When you take something on, say the shape of it out loud: what you will do, roughly how much time, and when it ends. Do the same when you ask something of someone else. Clear edges make it easier to say yes, and much easier to say yes again next time.