Pierce pork tenderloin with a fork to allow marinade to permeate through the meat.
Place pork tenderloin in a resealable plastic bag and pour in 1 bottle garlic and herb marinade(your preferred brand).
Cover and refrigerate. The longer the better!
Place pork tenderloin on aluminum foil and pour marinade over tenderloin.
Seal up foil with marinade and tenderloin, and wrap with foil again.
Place on low heat; grill for 30 to 40 minutes, turning often. Cook tenderloin thoroughly and serve.