Zhuge Liang to his son:

The practice of a cultivated man is to refine himself by quietude and develop virtue by frugality. Without detachment, there is no way to clarify the will; without serenity, there is no way to get far.

Study requires calm, talent requires study. Without study there is no way to expand talent; without calm there is no way to accomplish study.

If you are lazy, you cannot do thorough research; if you are impulsive, you cannot govern your nature.

The years run off with the hours, aspirations flee with the years. Eventually one ages and collapses. What good will it do to lament over poverty?

-from Mastering the Art of War, Thomas Cleary