Q. An aged individual who has a hard time walking and with effort stands only for shmonezrei, does he have to do the same for sefiras homer and the brocho before?

A. Although, besides the halacha that all mitzvah-brochos should be done when standing, there is a unique drosho on the posuk “Mehochel Chermesh Bakomo” (from the time the sickle is first put to the standing crop, D’varim 16: 9) that indicates sefirah should also be done while on foot, (Pesikta Emor, see Birkei Yosef 8: 2) however, it is only an “asmachta” (hint or intimation) and not a complete standard drosho. Therefore, after the fact you comply even when seating or lying down. (Shulchan Aruch O.H. 489: 1, Mishna Berura ibid. 6)

Horav Shlomo Miller’s Shlit”a opinion is that when possible, more effort should be placed on standing for the amida than for counting sefira.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a