Each of us, with discipline and effort, has the capacity to control his [or her] thoughts and his [or her] actions. This is part of the process of developing spiritual, physical, and emotional maturity.
President Gordon B. Hinckley, "Reverence and Morality", General Conference, April 1987
Maturity does not come with age, although it does come with experience, but, rather, maturity comes from discipline. Discipline to control thoughts and, therefore, actions.
It's interesting to read that not only spiritual maturity or emotional maturity come from discipline of the mind and actions, but also physical maturity comes from discipline of the mind and actions. When we control thoughts and, therefore, actions, we become more mature in every aspect of life.
It all boils down to controlling thoughts. Controlling thought = maturity = wisdom. That's how it's supposed to be.
"O, be wise; what can I say more?" - Jacob 6:12
Controlling thoughts is how we get there. We need to remove any negative thoughts taking over the spotlight of the mind.