Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Dice the chicken breast into 1-inch cubes and chop the broccoli, red bell pepper, and zucchini into bite-sized pieces.
In a small mixing bowl, whisk together the olive oil, fresh lemon juice, minced garlic, dried thyme, dried rosemary, sea salt, and black pepper.
Place the chicken and all the chopped vegetables onto the prepared baking sheet in a single layer.
Pour the lemon-herb dressing over the chicken and vegetables, then toss thoroughly with your hands or tongs to ensure an even coating.
Arrange the ingredients so they are spread out and not crowded, which allows the vegetables to roast rather than steam.
Bake for 18 to 22 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with slightly charred edges.
Remove from the oven and let rest for 2 minutes before serving to keep the chicken juicy.