Do not pray for your own needs, for your prayer will not then be accepted. But when you want to pray, do so for the heaviness of the Head. For whatever you lack, the Divine Presence also lacks.

This is because man is a "portion of God from on high." Whatever any part lacks, also exists in the Whole, and the Whole feels the lack of the part, You should therefore pray for the needs of the Whole.

-from a disciple of the Kabbalist R. Israel Baal Shem Tov