I recently got a new job, and I don't talk with people besides what is needed for work, because I'm in a time of my life where I don't want to interact with strangers if I don't have to.
My colleagues sometimes ask me to participate some free time activity. Usually I can make some excuse, like "I'm elsewhere just that day" or "I don't drink", or if it's a vague suggestion I can answer like "maybe some day". But once the question was like "let's do X some day, tell me when you are free". And X was something I couldn't find any excuse why I can't do it.
I know that he asked out of politeness and meant well. But he is in a position in the company that he is expected to be social with people, and I believe he asked because he was supposed to, not because he wanted to be social with me.
So the situation is, neither one of us wants to go, but he is expected to ask and I'm expected to go. How do I decline this request?