What motivated us to serve a mission? Simply our testimonies that the gospel is true and that the prophet asked seniors to serve missions. (It's hard to think that we qualify as "seniors" but the calendar says we do!) We've always known we would serve a mission in our "later years".
Both sets of parents served missions in their senior years. My dad had had a
stroke and had double vision and walked with a cane but they were still
able to serve a Family History Mission in Salt Lake City, Utah. My dad had not had
the chance to serve a mission in his youth (although he was a stake missionary for many years as a young married man) so this was a wonderful
experience for him and for my mom. My brother served a mission in France in his youth and he and his wife Sara served a mission in Mauritius as seniors. So my family definitely was thinking "missionary."
LeRon's parents have quite the story though. During the Korean War, there were fewer Americans who could
serve missions because of the military draft. So Seventies Quorums in
Canada were asked to provide missionaries. Seventies
Quorums at that time were in every local stake and they were generally
composed of married men.
LeRon's dad was 34 and married with two children. He had never served a
mission as a young man and he and his wife felt that he should volunteer for a
mission. When he left a year later for the Great Lakes Mission, his
wife was expecting LeRon. LeRon was born three months after his dad
left on his mission. Two years later, his dad returned home to continue
ranching and being a husband and father. LeRon remembers meeting his dad for the first time when LeRon was two (at least he thinks he does -- he probably remembers his mother's stories of LeRon's reaction when his dad came home -- but don't tell LeRon!)
In their senior years, LeRon's parents served three missions. LeRon and his four brothers all served missions in their youth. LeRon's older brother Wayne and his wife Judy have served two missions as seniors.
And our three sons -- Michael, Craig, and Eric -- have all served missions.
So with our testimonies of the Gospel of Jesus Christ and the missionary spirit in both of our families, how could we not serve a mission?!