It’s ok to be disappointed if you have a race that did not meet certain expectations or go as planned. It’s ok because it means you care and caring is a good thing. However, disappointment that has a long lifespan eventually just becomes a state of feeling sorry for yourself and that’s lame.
What disappointment must never lead to is complacency or giving up. It must be used as fuel that helps you refocus and reengage- it’s a negative emotion that must be redirected to positive action as quickly as possible.