Not an exact quote but adapted from this:
In that last interval set of each workout, remind yourself that it’s ‘this’ one that really counts. It’s always the last hill repeat, the last interval, the last week of your build cycle that really makes the difference. So dig deep in that last effort in order to really get the most out of the effort.
We all know, the last interval always hurts the most. Therefore my mantra:
It’s always the last interval which causes the adaptions.
Just used it today, 4x10 threshold intervals. The last few minutes hurt. The mantra helped.