The storekeeper wanted to carry them out to the waiting car. The Rosh Yeshiva insisted to do it himself.
The storekeeper agreed only after the Rosh Yeshiva said he insists in carrying them out because he wants the Mitzvah for himself.
Talmidim asked the R.Y. which Mitzvah he had in mind. He answered them "The Halacha in רמב"ם הל' דיעות פ"ד ה"ב"
"One should exercise daily in the morning"