In isolation intense exercise makes you weaker, depletes your energy systems, damages your muscle fibres, accelerates your heart rate, raises blood pressure, releases stress hormones and fatigues your nervous system… hardly a prescription for optimal well-being.
Throw recovery into the mix and the equation changes. Given sufficient time, calories and nutrition to repair and regenerate the body will fortify itself against the physical stress of the workout. This is when you build muscle, improve energy systems, strengthen connective tissues and become physically more capable. Not during the workout, after the workout.
Exercise therefore is the trigger, not the benefit. Adaptation to exercise is the benefit. Don't sell your workout efforts short by neglecting the recovery-piece of the fitness puzzle.