Building on the explanation of why מצות are called "Hashem's way", the רבי רש"ב emphasizes that Interstate 613 must be a two-way street. Hashem sends down תורה, and we send back our מצות. This happens when our מצות are done, not out of rote, but with self-scrutinization and pushing oneself past the comfort zone.
When you do a מצוה, specifically when it is hard, you are showing up to the relationship, fulfilling the point of Hashem having given the תורה!