The Torah commands us to serve Hashem out of a sense of love and adoration. The Talmud in Nedarim (62a) comments on the above posuk – One should not say, “I will study scripture so that I will be called a wise man, I will study Mishnah so that I will be called a Rabbi, I will study Mishnah so that I will become an elder and sit in the yeshiva.” Rather, learn out of love for Hashem and eventually honor will come. One should not study Torah for personal reasons and ulterior motives, but rather Torah should be studied “lishma” (for its own sake) simply because it is our Divinely given guide to life. We should not use Torah as a vehicle by which to gain status and prestige. Although seeking prestige through Torah indicates our appreciation of it, this should not be the focus of Torah study. If we assume such a shallow approach to Torah study, we will remain nothing more than callow and capricious individuals who do not represent the ideals of a “ben Torah.”
The Chasam Sofer notes the emphasis placed on “lishma” (for the sake of a specific mitzvah) in three areas: Torah, marriage, and performance of good deeds. These three arenas of Jewish endeavor demand that one be sincere and straightforward. These mitzvos are more than exercises in human nature; they are the fulfillment of a religious obligation. To perform them with a tainted perspective is to render them a crippling blow. He explains the blessing at a circumcision and a redemption of the first born “Just as he entered the (covenant) (redemption) so may he enter upon the study of Torah, marriage, and the performance of good deeds).
These two milestones are performed purely for the sake of the mitzvah. Neither the parents, nor the infant, have any ulterior motives whatsoever. These are rituals which are mandated by Hashem, and likewise performed. The child is given this special blessing at these two occasions, wishing him, that just as he has “participated” in these two mitzvos, purely out of religious observance, untainted by any unworthy side interests, so may he merit to perform these three other mitzvos out of sincerity and purity of heart.