The answer to each question is commitment to their faith and Church. This is coming from a "Gentile". The Mission experience, purely from the standpoint of maturation, is something that the rest of the world should respect and even envy.
While still in AROTC I went to a Korean restaurant with my DS and his Mormon wingman. The wingman did all the ordering, in Korean, and we were treated like kings. Afterward, they hit the college bar scene and I slept well knowing that my DS had a designated driver, who needed no designation.