how to get over someone?

How can I stop thinking about someone? I met a guy. There is zero chance of getting together. We don’t have any contact with one another. We just had a really nice time for a brief moment in time. Intellectually, I don’t want to get together. There are little want matches beyond the physical. I can list a ton of reasons why that person is not a good fit for me. It’s been 9 months since I last saw this person. Why can’t I seem to move on? I don’t have any ill feelings for him. I’m so grateful for the opportunity we had to get to know one another. I wish him the best but I’d like to not think about him so much.