The gemara (Sota 14) writes that Hashem responded to Moshe’s request to enter Eretz Yisrael by saying “If all you want is the reward of mitzvos hateluyos ba’aretz I will give them to you without your entering the Land”. The Yismach Moshe connects this response to a Midrash that Moshe involved himself with removing Yosef’s bones from Egypt only for the sake of schar mitzvah – midah k’neged midah, just as Moshe began the journey from Egypt to Eretz Yisrael by focusing on schar, this in the end prevented his entering the land. (As to why Moshe was motivated by schar and not lishma, ayen sham, or maybe more on that later).
The Maharasha makes an interesting point with regard to the motivation of schar mitzvah: since Moshe was not yet obligated to do any of the mitzvos hateluyos ba’aretz, there was nothing wrong with being motivated by schar to want to become obligated by entering the Land. Our wariness for performance “al menas l’kabel pras” extends only to someone who has an obligation and discharges it solely to receive reward; someone who has no obligation but wants to undertake greater obligations faces no such test of having proper intentions.
Apropos of the latest round of discussions (here, here) of amein/tefilah groups, I wonder why when it comes to women performing mitzvos or learning Torah there is an immediate suspicion of improper motive. Could one not argue based on the Maharasha that any cheshbonos of “al menas” apply only to someone who is already metzuveh; for someone who wants to undertake an extra obligation there is much less of a burden to insure and insist that motives be “lishma”.