Why do we need to know about שרה's life span? How is this opening פסוק - like every פסוק in תורה - a lesson and an empowerment for every Yid?

The רבי quotes the זהר, as explained by the generations of רביים before him, which guides us through סדר השתלשלות, and seeing it reflected in the פסוק's description of שרה's life. As we tour our inner psyche, we see how שרה's life is a guide for us to live a wholesome and perfect life.

But, how does this explanation of חסידות fit with רש"י's explanation of the פסוק?