Preheat your oven to 400°F (200°C).
In a small bowl, whisk together olive oil, juice from the lemon, finely chopped garlic, thyme, rosemary, and a pinch of salt and pepper.
Place the chicken breast in a baking dish and coat it evenly with the lemon-herb mixture.
Chop the broccoli, carrot, and red bell pepper into bite-sized pieces and toss them with a drizzle of olive oil, salt, and pepper in a separate bowl.
Arrange the vegetables around the chicken in the baking dish, ensuring they are spread out for even roasting.
Roast in the preheated oven for about 25-30 minutes, or until the chicken is cooked through and the vegetables are tender and slightly crispy on the edges.
Remove from the oven, let rest for a few minutes, then serve drizzled with any remaining pan juices and a squeeze of extra lemon if desired.