That is where learning your temperament can be helpful. I am introverted. I know I need to have my alone time to recharge. If someone called and invited me out during one of these times, I would have to decline the invitation or just not answer a phone call. Part of me used to feel guilty as if I was letting people down and being mean to them for not wanting to join them or even acknowledge them. This sometimes depressed me. But I have since come to know that it's ok for me to feel this way. It is as much a part of me as my blue eyes. So now I will answer the phone and just explain that I am feeling tired and will meet them out next time. The person is understanding the vast majority of the time. We sometimes judge ourselves too harshly because society beats it into us that we have to be or act a certain way.