Everyone has their own opinions of what it means to be mature. It's not just a product of aging, but rather a mindset that is found in different people—some old and some young.
This is Maturity...
… is the ability to control anger and settle differences without violence or destruction.
… is the patience, the willingness to pass up immediate pleasure in favor of the long term gain.
… is unselfishness—responding to the needs of others, often at the expense of one's own desires or wishes.
… is the capacity to fare unpleasantness and frustration, discomfort and defeat, without complaint and collapse.
… is humility. It is being big enough to say, "I was wrong", and when right, the mature person need not say, "I told you so".
… is the ability to make a decision and stand by it. The immature spend their lives exploring endless possibilities then do nothing.
… means dependability, keeping one's word, coming through in a crisis.
… is the art of living in peace with that which we cannot change.