Place the boneless skinless chicken breasts in a large tupperware or plastic Ziploc.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, garlic, rosemary, parsley, basil, salt, and pepper.
Add the lemon garlic herb marinade to the chicken, making sure to coat each chicken breast in the marinade.
Marinate at least 30 minutes, or up to 8 hours. Alternately, you can freeze the chicken and marinade at this point. If you freeze it, be sure to remove it from the freezer the evening prior to cooking, to thaw in fridge.
Preheat the grill to medium-high heat. Grease the grill grates.
Once hot, add the chicken and cook for 6-8 minutes on each side, or until an internal thermometer reads 165 degrees F. Because of the difference in sizes of chicken breasts, I highly recommend using a meat thermometer to determine when the chicken breasts are done cooking - it's the most accurate way!
Serve and enjoy!