In order to make space within Himself for us, Hashem "contracts" His Infinity, so to speak. When we contemplate on the fact that this is all done in order to create the possibility of a relationship with Him, it will trigger within us reciprocal feelings of wanting to "contract" ourselves for Him, ie. to prioritize His will even at the cost of our personal desires.

Based on Chapters 48-49 of Tanya.