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.

Why is it so important that we mirror back Hashem's Light through our מצות?

The first explanation is because that is how we complete the road; the true point of the King coming down to the village is for the village to be raised back to him.

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!