Set your oven to 400 degrees Fahrenheit and prepare a baking sheet by spraying it with nonstick spray.
Cut the chicken breasts into bite-size pieces and place them into a large mixing bowl.
Slice the zucchini and yellow squash into rounds, then dice the bell pepper; add all these vegetables along with the cherry tomatoes to the bowl with the chicken.
Combine olive oil, lemon juice, minced garlic, Greek seasoning, salt, and cracked pepper in a small bowl and whisk until blended.
Pour this seasoning mix over the chicken and vegetables, tossing gently to ensure everything is evenly coated.
Arrange the chicken and veggies in a single layer on the prepared baking sheet and bake for 20 minutes, or until the chicken is thoroughly cooked.
Once out of the oven, sprinkle the top with crumbled feta cheese before serving for a delicious finishing touch.