This an old story, starts with a space cadet starting at the academy, all the hard work getting through it, a lecture about the core sentence 'God bless you', the cadets qualifying and jetting off everywhere. It ends with one of the cadets coming back years later as the commodore, remembering everyone and most especially one of the staff members and saying 'God bless you'.
That is Eric Frank Russell's "Minor Ingredient" which appeared in the March 1956 Astounding. (See http://www.isfdb.org/cgi-bin/title.cgi?55771 for the ISFDB report on it.) I've had no luck finding it online, though.
It starts cadet Warner McShane arriving at the Space Training College and seeing the motto "God bless you." It ends, with an old cadet returning and looking through old books at pictures of long-dead staff:
Squaring his gold-braided shoulders, Fleet Commander McShane said in soft low tones, "God bless you!"
And turned the page.