The second parsha of Krias Shema, Vehaya im shamoa, is referred to by Chazal as kabbalas ol mitzvos. When we say the words of this parsha, we should focus on the idea that the only way to serve Hashem and show our loyalty to Him is by observing the mitzvos. There is nothing else we can do that will substitute for this.
But what Hashem wants most from us is not just to go through the motions of doing the mitzvos. "Hashem desires the heart." A true ben Torah feels close to Hashem.
Adapted from Emunah in the Classroom