Yeah, I'm sure you really took it to heart after giving it all of 2 minutes from the time I posted 'til the time you replied.
lol
Keep on slappin' the ground and punching walls, kid. Then let me know how your hands and arms are in a couple decades. I have a lot of old karate pals with big, swollen, sore knuckles from a mispent youth of pounding makiwara...until they learned that it was all about the hips and ground, not the hands. I've been training and observing for 30 years now, but I used to buy into the "conditioning" stuff when I was young.
Same for slapping hard ground. Go on out and hit the bricks. Literally! See what it does for you. But sooner or later you'll realize it's all about being soft and relaxed, and using good form -- not slapping.