W. Austin Gardner
Essential qualities

"These three qualities -- peace, joy, and courage -- are essential to missionary service. Fear is one of the most disintegrating forces in the human personality. It can paralyze a person to the point where he is incapacitated for any kind of constructive work. A timid, joyless, troubled missionary won't last long on the mission field." page 205
Christian Missions in Biblical Perspective by J Herbert Kane