Self Improvement Made Easy

So much advice tells us to 'be ourselves' or 'be true to ourselves', and yet we would all agree that it behooves us to undertake a certain amount of self improvement e.g. if someone tells you that you are rude, it would be worthwhile makeing an attempt to be more courteous, the same goes with other things like being more confident, more loving, more literate, more open minded, more healthy etc.

This contradiction has been haunting me for years. I would very much like to change and improve myself, but I keep being told that I should just be myself. What am I supposed to do?