Say "no" every time i feel like it and not feel guilty

I said no to my boss today, but I still feel guilty over it. I was supposed to work but she called me and said business was slow and she didn’t need me. Therefore, I made other plans. Three hours later she calls and says she is swamped and needs me to come in. Well, I was already busy doing something so I told her sorry, but I can’t. If I did not have anything else to do I would have went in, but I had plans and I believe I was well in my right to say no. Regardless, I still feel guilty about it.

I did say no today, and I refuse to feel guilty about it. A friend called wanting me to go somewhere with her. I had told her I would probably go with her, but she called me yesterday and said she was getting a ride with a girl she had met the night before. She said I was still welcome to come, but there is no way I’m tagging along, especially with someone I don’t know and she knows that. So today she called and the girl probably can’t go, so will I go with her? No. I’m well within my right to say it and no, I do not feel guilty about it. She has bailed out on me a lot before and telling me she is going with someone she just met, well knowing I would not be comfortable going, is one more time. So I wasn’t planning on going anymore and just cause she called I’m not changing in plans to accomodate it.

I have gotten better at saying no, but there are still those times when I should, but I just can’t say no. I think my major problem is the not feeling guilty part. It seems like when I do say no, I just can’t help but feel guilty about it. Like I have let someone down or done something wrong even though I am aware that is not the case.

It’s not like I can’t say no. I can do it, but the people I have to say it to usually end up trying to make me feel like shit. And it usually works to. Most of the time I’m just like whatever, I just don’t won’t to put up with the after effects. I really shouldn’t make my life revolve around trying to keep others happy. They treat me like shit a lot and sure as hell don’t attempt to keep me happy, why the fuck should I do it for them?