Sharpen the saw means preserving and enhancing your greatest asset you have --- you!
It means having a balanced, systematic program for self-renewal in the four areas of our lives:
Without this discipline, the body becomes weak, the mind mechanical, the emotions raw, the spirit insensitive and the person selfish.
i) The physical self is the body. We build its strength through nutrition, exercise and rest.
ii) We exercise our mental self through learning - reading, writing, challenging and taking time to think.
iii) We exercise our social-emotional self by making consistent daily deposits into the Emotional Bank Accounts of our key relationships.
iv) We exercise our spiritual self through reading literature that inspires us, through meditation or prayer/solat and through spending time with nature.
(Source: The Seven Habits of Highly Effective People by Stephen R. Covey)