Why is anticipation greater than realization for earthly things but not for eternal things?
Earthly things perish, so once they are obtained, the excitement of anticipation fades into a letdown. Eternal things are above, centered in Christ, and their fulfillment will exceed the anticipation. Believers are to seek those things above and set affection there, making heaven their first priority.
Les teaches from Colossians chapter 3 that being risen with Christ changes our appetites and desires. We are to seek those things which are above, which are eternal, where Christ sitteth on the right hand of God, and set our affection on things above, not on things on the earth. He illustrates this with earthly things: he wanted a particular make and model of car, finally got it, and then found that anticipation is a lot more exciting than realization. Once realized, it is just blah. But with eternal things, anticipation is great, and the realization is going to be greater. Therefore, priorities matter: heaven is where we have our first interest, while things perish.