Your mind is your most important tool in life.
It is a machine, and as with every other super computer you need to make regular updates, clean out the cache and upgrade.
A lot of people stop learning and feeding their brain when they get out of school. If I stopped learning when I got out of college, I would have missed out on 6 years of growth as of today.
Every action, every word, every emotion starts with the mind. Nurture it properly.