This is a great topic!
I HATE being the person who is always canceling because I know what it's like to be on the receiving end of it. When I know I'm not well or up for an event, it really gets my anxiety going. I'm continually going back and forth in my mind thinking "what if they get mad?" or "what if I go and I'm miserable?" It's a psychological battle every. single. time. It never gets easier.
I've really had to learn to give myself grace in these situations. For the most part, the people I'm canceling on know that I'm sick and luckily are very understanding. I've lost a few "friendships" because of it, but I firmly believe that those were just not my people and not who I need in my corner at this point in my life.