It all started with reading 1 John 3:2-3.
Dear friends, now we are children of God, and what we will be has not yet been made known. But we know that when he appears, we shall be like him, for we shall see him as he is. Everyone who has this hope in him purifies himself, just as he is pure.
Apparently, we are sanctified by meditating on both seeing Jesus face-to-face and the transformation we will experience when we see him. In other words, it is good to think about heaven.