Assertiveness is healthy and it does not intend to hurt someone. If you see your intent in this light, perhaps you would be able to be more choosy (because an un balanced relationship is going to be an unhealthy relationship) Honesty with self and others is what will bring balance.
Try not to be hard on yourself (you're also human) If you try to make yourself busy you're only using a defense mechanism and not dealing with the issue at hand. Instead, try to see if there are any underlying reasons behind your behavior such as desire to please, seeking acceptance, trying not to disappoint, etc. Then focus on those feelings as the source of the behavior. Journaling can be quite helpful as well as accepting that you cannot please everyone but ought to at least please yourself.
Yes, I am trying not to dissapoint people, but I feel I am going to hurt their feelings