Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Wash the zucchini and yellow squash, then slice them into 1/2-inch thick half-moon shapes.
Cut the boneless, skinless chicken breast into 1-inch bite-sized pieces for even cooking.
In a large mixing bowl, combine the chicken, zucchini, and squash with the olive oil, minced garlic, dried oregano, sea salt, and black pepper.
Toss the ingredients thoroughly until everything is well-coated in the oil and spices.
Spread the mixture onto the prepared baking sheet in a single layer, ensuring the pieces are not overcrowded to allow for proper browning.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
Remove from the oven and immediately drizzle with fresh lemon juice to brighten the flavors before serving.