How?

How do you keep away from people/person and places that can spoil your mood? I guess never!!!! I believe I should practice the art of keeping mum and just go with the flow. The sad part is this people/person mess up the atmosphere each time he/she/they start talking. Some times thinking about seeing him/her/them ruin my entire day. I know its bad feeling sick of him/her/them, but what should I do? Please tell me! I need your advice!