If using wooden skewers, soak for at least 30 minutes.
In a large bowl add chicken, olives, onion, garlic, lemon juice + zest, olive oil, oregano, salt and pepper. Toss to coat and marinate for 30 minutes - 24 hours. The longer meat marinates, more flavourful it is and cooks faster.
Chop veggies while meat marinating and you can refrigerate them as well. Prep skewing station.
To skewer kabobs, here is the order I used - you can use any: 2-3 chicken pieces, onion, 2 olives, zucchini, tomato, 2-3 chicken pieces, 2 bell peppers, onion. Discard remaining marinade.
Preheat grill on medium heat, around 500 degrees F, and spray with cooking spray.
Grill skewers with lid closed turning every 2 - 3 minutes for even grilling. Kebabs are ready when chicken is cooked through, about 8 minutes.