Be selective about whom you take on as friends, colleagues, and neighbors. The world is full of agreeable and talented folk. The key is to keep company only with people who uplift you, whose presence calls forth your best.

But remember that our moral influence is a two-way street, and we should thus make sure by our own thoughts, words, and deeds to be a positive influence on those we deal with. The real test of personal excellence lies in the attention we give to the often neglected small details of our conduct. Make it your business to draw out the best in others by being an exemplar yourself.

Epictetus
The Art of Living (San Francisco: Harper Collins, 1994), 54