Cooling down and stretching matters so much when training! Without doing both on a regular basis, we risk fatigue, injury and a reluctance to train. Which is to be avoided, oui?
It is tempting to skip either a cool down or stretching when a workout is finished, but taking a few minutes to do either (or, ideally, both) really pays off and can also boost energy levels and the ability to recover fully from a demanding workout.
So cool down and stretch whenever possible (and don't forget to warm up either!).