When she misses a workout she counts it as gained.
That bad day happened and the speed workout got kicked out. This is how life is. You can't get around the fact that today there are only so many options and running the first hard workout of the week will not happen. So wipe it away and understand the value of rest. At least on this day strength is gained because it is at rest that the body rebuilds. It is not for a lack of motivation or planning that a run was missed. Next morning, the sun will rise in the east and another chance to snatch a fast pace on the watch.
Patience and understanding that this road will twist and turn but is still going in the right direction.