When considering himself, shaggy thinks, "while i am not any of these things, i should be smart, i should be nice, i should be good at sports." these thoughts best represent shaggy's?

I believe the answer is: Ideal self

Ideal self refers to a perception of what we could be when we are fully achieve our self actualization. This ideal self usually would be used as a foundation for people when we're choosing the decision that we should take at this very moment.