How to politely say "No"

Rihana's point is the first thing that came to my mind too.

But other than that, I overcame similar things by learning to not care about what they think. I force myself to not think how they feel and concentrate on what is fair and logical and right. and just do the required thing.

For example. not wake up before I want to. Not attend to guests or show interest in talking to them if they have been invited without my consent. I'd just greet them and say I have something to attend to - I'll catch up with you in a while and go to my room

When preparing extra food, i pack it into little boxes and label the boxes "monday", "Tuesday" etc. then it will be harder to use it to serve to guests and i wont have to tell no to anyone.

How to politely say "No"