Afraid
Part of speech: adjective
Definition: Impressed with fear or apprehension; in fear. regretful, sorry
Example sentence: If you're afraid to fail, then you're probably going to fail.
Concerned
Part of speech: adjective
Definition: in a manner showing concern.
Part of speech: verb
Definition: To relate or belong to; to have reference to or connection with; to affect the interest of; to be of importance to.
Example sentence: During a political campaign everyone is concerned with what a candidate will do on this or that question if he is elected except the candidate; he's too busy wondering what he'll do if he isn't elected.