How do you pick yourself back up after a disappointment?

I was recently moved to a different section, and though nobody said anything about my doing my job inadequately, I feel like it was because of that. I don’t know if I am making up nonsense in my head to make myself feel bad, or if I am right, but I do know that it doesn’t matter. Right? I am trying to embrace this change but I end up just clinging on to all the negativity of it. Why do I do this? More importantly, how can I rid of it?