What Would I Have Done Without the Ohr HaChaim
Rav Yaakov Yosef of Skver spoke often of how important it is to study the Ohr HaChaim HaKodosh. He once said, "Ich veis nisht viazoy ich valt gekent a'durech di letzteh fiftzig yohr ohn Ohr HaChaim - I don't know how I would have survived the last fifty years of my life without the Ohr HaChaim." He studied it from the age of six, and it stayed with him all his life.
Source: Toldos Yaakov Yosef Skver, p. 22