Marinade the meat in an acid to help tenderize the meat. Let the meat marinate for 24 hours. You can help to accelerate the marinade process by storing it in a vacuum-sealed bag. Try ingredients like pineapple juice, soy sauce, or vinegar. Also, be sure to cut the meat across the grain. This prevents the sliced meat from being chewy and allows the natural fibers in the meat to tear apart more easily when eaten. And don't overcook the meat. For steak, cook it to a perfect rare or medium-rare. For chicken breast, don't cook it any higher than a 160°F to 165°F internal temperature.