Remember, the chicken will still cook a bit after it’s removed from the grill (as I mentioned above). However, there are some tips you can do to tenderize the chicken breasts prior to it even going on the grill. When I want a really tender chicken breast, I’ll use a meat tenderizer (or a rolling pin) and pound the chicken breast a bit in the really thick portions of the breast. This helps get an even thickness of the breast so you get an even grill and aren’t stuck with parts of the chicken being too dry. Then you can add the chicken breasts to the marinade.