Contemplating the unfathomable greatness of God generates an appreciation of how distant we are from Him, of how exalted and awesome He is.
This causes a shriveling of the self, which perceives its insignificance before what is immeasurably greater than itself and to have the fear of God in his heart.
This is the resultant emotion of that awareness: fear of God.
In turn, his heart will glow with an intense love like burning coals, with craving, desire, passion, and a yearning soul, towards the greatness of the Blessed Infinite.
The same truth, contemplated from a different angle, produces a love of God: the desire to connect and fuse with His great and magnificent being.
–Rabbi Adin Steinsaltz
From Opening the Tanya, p.113, by Rabbi Adin Steinsaltz