In a large bowl, whisk together the olive oil, lemon juice, garlic, oregano, salt, and pepper.
Add the chicken pieces to the bowl, toss to coat, and allow to marinate for 20 minutes.
Heat a large non-stick skillet over medium-high heat.
Add the chicken and marinade to the skillet; cook, stirring occasionally, for 8 to 10 minutes until the chicken is browned and cooked through to an internal temperature of 165 degrees Fahrenheit.
Prepare four serving bowls by placing 0.5 cup of cooked rice into each bowl base.
Divide the cooked chicken, diced cucumbers, halved tomatoes, sliced red onions, and olives equally among the bowls.
Garnish each bowl with 1 tablespoon of crumbled feta cheese and 2 tablespoons of tzatziki sauce.