I have suggested that the three main characteristics of a good missionary are:

• Willingness      (a volitional quality)
• Flexibility         (a psychological quality)
• Resiliency         (a spiritual quality)

<You may feel that “spiritual” is the wrong word, but if one accepts the definition of spiritual as the intersection of power and meaning, a lack of resiliency means either a breakdown in power/determination or wavering of meaning/purpose. Within the Christian context, such meaning/purpose is largely found in Christ.>

Focusing on the 2nd quality, psychological flexibility, the following quote is provided

“Missionary work, though it may occupy a missionary’s lifetime, is essentially temporary in nature.  The missionary always looks forward to the time when this part or that, or even the whole work will be completed. What does this mean to the missionary? It means that if he is a competent worker, one of two things will happen. Sooner or later he will have to change his location, as each job is completed; or he will have to have the mobility within himself to change his type of work as the old needs are filled and new ones present themselves. In either case he needs to be mobile.”

-Quote from Harold Cook in “Maximum Impact Short-Term Mission” by Peterson, Aeshliman, and Sneed.  p. 210-211.

This “mobility’ is essentially psycho-emotional flexibility. If the quote included cultural flexibility, I think it is approaching the broad sense of the quality in missionaries.