Ease is what repetition leaves behind. It arrives last rather than first, and quietly enough that most people miss the day it turned up. Consider two years of avoiding the motorway — slip roads, junctions, the long way round to absolutely everywhere. Then one spring a trip to the coast gets planned and the route simply never comes up in the conversation.
Nothing dramatic happened in between. Somebody just kept getting into the car on the days when it was still frightening, until the fright ran out of new material.