Preheat the oven to 400°F.
In a small bowl, mix olive oil, minced garlic, chopped rosemary, thyme, salt, and pepper.
Rub the chicken breast with the herb mixture ensuring even coating.
Place the seasoned chicken on a baking sheet and roast in the oven for 20-25 minutes or until fully cooked and juices run clear.
While the chicken is roasting, prepare the Greek yogurt salad by mixing the nonfat Greek yogurt with a pinch of salt, pepper, and a little chopped fresh herbs if desired.
Once the chicken is done, allow it to cool slightly before slicing.
Toast the whole wheat bread lightly if desired.
Assemble the sandwich by spreading a layer of Greek yogurt on both slices of bread, adding a bed of romaine lettuce, placing the sliced herb-roasted chicken, and topping with tomato slices.
Serve immediately and enjoy your balanced, flavorful sandwich.