Prepare the chicken marinade. Whisk together the oil, garlic, lemon juice and zest, fresh chopped herbs, salt and pepper. Place the chicken breasts in a shallow dish. Pour the marinade over the chicken breasts. Cover and refrigerate for at least one hour.

To cook the chicken, heat a grill or grill pan over medium-high heat. Place the marinated chicken breasts directly onto the grill (immediately discard all remaining marinade). Cook for 5 to 7 minutes, then reduce heat to medium. Flip the chicken breast over and cook for an additional 5 to 7 minutes, or until a thermometer placed in the thickest part of the breast reads between 160 and 165 degrees Fahrenheit.

Remove the chicken from the grill and place on a plate. Tent the plate with aluminum foil and let the chicken rest for 5 minutes before slicing and serving.

While the chicken is cooking, prepare the four bowls. Place 3/4 cups of cooked brown rice and 1/2 cup baby spinach into each bowl. Divide the tomatoes, olives, cubed feta, tzatziki, red onion slices, and cucumbers evenly between the bowls.

Slice the cooked chicken breasts and place them onto the bed of spinach in the prepared bowls. Garnish each bowl with a slice of lemon and a sprig of fresh dill. Serve immediately.