Place a chicken breast between plastic wrap and, using a meat mallet or rolling pin, pound to an even thickness. Repeat with remaining chicken breasts, then set aside.
Chop the thyme, sage, rosemary, and garlic, then place in a (mini) food processor.
Zest a lemon into the processor, then add the sea salt and ground pepper. Place the lid on the food processor, then pulse a few times until well combined.
Add 1 tbsp of olive oil to the food processor, replace lid, and pulse again until mixture is a paste-like rub.
Rub each piece of chicken (both sides) with the lemon-herb rub, then place the chicken in a small baking dish so that pieces are close together. Pour the lemon juice over the chicken pieces, cover the dish with plastic wrap, and place in the refrigerator to marinate for 3-4 hours, or up to overnight.