Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
In a small mixing bowl, whisk together the olive oil, lemon juice, minced garlic, dried oregano, dried thyme, sea salt, and black pepper to create the marinade.
Place the cubed sweet potato, broccoli florets, sliced red bell pepper, and sliced zucchini onto the prepared sheet pan.
Drizzle exactly half of the lemon-herb marinade over the vegetables and toss them thoroughly until they are evenly coated.
Place the chicken breast in the center of the sheet pan, moving some vegetables aside if needed, and brush the remaining marinade over both sides of the chicken.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and slightly browned.
Remove the pan from the oven and let the chicken rest for 5 minutes before slicing to ensure the juices stay locked inside.