Although Sweetheart and I had been planning to serve a mission when we retired, we found several very important reasons to delay. That changed when Marty came home from a meeting where very strong counsel was give for retired couples to give of their time to assist in missionary service. (http://www.lds.org/general-conference/2011/10/we-are-all-enlisted?lang=eng) He came to me and said, "We've been called to serve a mission!"
That enthusiasm quickly diminished in the face of reality - medicals needed (and him with serious heart problems and me with diabetes); selling our beautiful home was essential so we could leave without debt; moving to our cabin in the mountain, which we own without debt (and which is fun, but very small); selling my dream grand piano as there is no space in our cabin for it; seeing our youngest son (recently home from his mission in South Africa); worrying about both of our mothers in their 90's; etc., etc.
Studying scriptures, praying earnestly, exercising faith brought about great miracles and all is now in readiness for us to pack and be on our way.
It is a very emotional time as we leave family and friends and home for the unknown, but we have learned to "trust in the Lord with all our heart and lean not unto our own understanding." (Proverbs 3:5) Also, to "Look unto the Lord in every thought: Doubt not, fear not." (D&C 6:36)