the way to a man's heart is through an analogy about his stomach
The Baal Shem Tov explains that this world is like an ice-cream* store. When you enter the store, they give you a taste of the goods, and then when you want more, they demand money. So too with HaShem, when you first begin to draw close to HaShem, everything comes easily. When you realize you want more, then HaShem makes you work for it.
* I chose the ice-cream store as the particular kind of store - which made for a simpler translation. ** this is sourced in Ketem Ofir 2:19 by the Komarna Rebbe