Codependency Support Group
Codependency is defined as someone who exhibits too much, and often inappropriate, caring for another person's struggles. A codependent person may try to change, or feel shame about their most private thoughts and feelings if they conflict with the other person's struggles. If you are on a journey towards self-love, this support group is for you. Join us and find others...

I have had trouble with that as well. Somehow I had the belief that I could not say "no" to requests (not polite or nice to do that) and everyone else's requests were more important than mine.
What happened with this person today? Were they rude to you or trying to take advantage of you in some way?
Please be kind to yourself. In order to change, we have to learn new behaviors and coping skills. It is not easy to do that when the old ways are so automatic.
When you are not upset, either ask a friend or someone you can trust, what an appropriate response might have been. Baby steps.
Shar