Eleanor Roosevelt's book "You Learn by Living" has a chapter on maturity. Below is a paragraph from that chapter that I think nicely sums up maturity:
"One must be willing to have knowledge of oneself. You have to be honest with yourself. You must try to understand truthfully what makes you do things or feel things. Until you have been able to face the truth about yourself you cannot be really sympathetic or understanding in regard to what happens to other people. But it takes courage to face yourself and to acknowledge what motivates you in the things you do."
How true! Especially the part about courage. But with courage comes contentment, and that is the best present you can give yourself.