In a large bowl, add the chicken pieces, olive oil, lemon juice, oregano and salt and pepper. *Let marinate for at least 30 minutes in the fridge.
Cut up the veggies and prepare the string the skewers.
Once the chicken has marinated, string the chicken pieces, red onion pieces, bell pepper pieces, zucchini pieces and olives.
Grill for 10-15 minutes, rotating 2 or 3 times, until chicken is cooked through and veggies have softened. Grilling time may vary depending on heat on the grill and size of the chicken pieces.
Serve Greek Chicken Kebabs with simple side salad.