"You have to learn as long as you're ignorant; if we believe the maxim, that's as long as you live. This maxim coheres best with the following: you have to learn how to live as long as you live. Anyway, I also teach them something at the school. You ask what I teach? That even an old man has to learn." -Lucius Annaeus Seneca
Never stop learning, not for one instant think that you know all things. Remind yourself daily that you have so much to learn and so little time to do it. Even when I am old and infirm, if I have the capacity to learn I will exercise it. And when I do not I will pass away without shame.