You are anxious because you are not confident!
You may have a crush on this man, but you don't know if he feels the same way. So anxious.
If you are an adult, confess quickly and let the other person know your heart. If you succeed, seize the opportunity and continue to develop; If not, give up resolutely and look for the next goal. Don't waste time and energy.
If you are not an adult, don't care too much, improve yourself and develop gradually in the interaction of ordinary friends.