When we ask someone else to do something for us (or to refrain from doing something that annoys us) we often don’t know what it would cost them. Because we tend to forget that we’re all different, and so what seems like a simple request to me may actually sound to someone else like an impossible request, like I’m asking them to climb a mountain before breakfast.
So when we ask someone to do us a favour or to take on a job or to please stop doing such-and-such because it drives us up the wall, we can’t just assume that they can, and we can’t assume that we know what it would cost them. So we must leave plenty of room for them to say no.
The other side of the coin is this: when you agree to do what someone has asked, be aware that they probably don’t know what it’s going to cost you. Don’t expect their level of appreciation to match your effort. If they think they’ve “only” asked you to lift one kilo but they don’t realise that the state of your muscles is such that lifting “a whole kilo” is very hard for you, then they’re not likely to show a huge amount of gratitude. Which means it’s also up to you to weigh up the cost before agreeing – you’re the only one who knows how hard/easy it would be for you.