Neurons have projections called dendrites that bring information to them from other cells and generally longer projections called axons that take information away.  Research shows the more you use your brain the better it is at maintaining and creating new axon and dendrite connections.
We now know that our neural networks are more plastic, meaning capable of change.  Research is finding that “it takes less than two weeks for a neuron to grow new axons and dendrites”.[i]  For a long time, it was believed that older people could not rewire their brains through new learning.  It was believed that habits were more ingrained.  Through the work of the fruit of the Spirit in us, our brains have the capacity to rewire even into our advanced years.  When we practice something, our neural circuitry strengthens in helping us to remember and carry it out into the future.  The more that our neural circuits fire together in healthy ways, the stronger these pathways become.  The more that our will and desire are geared toward love and goodness, the more that our whole person will become an expression of God’s goodness.
[I]  Andrew Newberg and Mark Robert Waldman, How God Changes Your Brain: Breakthrough Findings from a Leading Neuroscientist, (New York: Ballantine Books, 2009), 104.