The Rebbe writes that the merit of being careful with the mitzvah of Tzitzis, especially influencing others in this area, brings blessings of long life, good health, and chassidic nachas. He references teachings about the greatness of Tzitzis and offers blessings for the recipient and his family.
https://www.torahrecordings.com/rebbe/igroskodesh/011/009/3578