Leo didn't have to wait for long; the influx of energy came again less than a second after he collapsed.
"This is great!" Leo thought gleefully.
From his experience with the old martial art, he had discovered another route to getting stronger without having to kill anything. While this method was undeniably slower than killing zombies, Leo's excitement wasn't dampened because of this.
Though there were still a lot of questions relating to the martial art of the old man he memorised in that vision, and there were a lot he didn't know about it, a part of Leo believed that the effect he had just discovered from practising it was just the surface of its overall mystery.