The middle is where the goal asks whether you wanted it or merely enjoyed wanting it.

Wanting something is genuinely pleasant. It comes with anticipation, with a story about your future, with none of the tedium. The middle strips all that away and leaves only the work, and that is where you discover which of the two you were actually attached to.

When the middle arrives and the desire thins out, do not treat that as a verdict yet. Keep going for a defined period and then decide. Judgements made at that moment are usually about the loss of the pleasant part.