Preheat your grill or grill pan over medium-high heat.
In a small bowl, combine lemon juice, olive oil, minced garlic, dried oregano, dried thyme, salt, and pepper.
Place the chicken breast in a resealable bag or shallow dish and pour half of the marinade over it. Let it marinate for at least 15 minutes.
Meanwhile, toss the broccoli florets with a pinch of salt, pepper, and a drizzle of olive oil if desired, and spread them on a baking sheet.
Roast the broccoli in a preheated oven at 425°F for about 15-20 minutes, or until tender and slightly charred.
Grill the marinated chicken breast for about 6-7 minutes per side, or until the internal temperature reaches 165°F.
Prepare the quinoa according to package directions if not already cooked.
Plate the grilled chicken alongside the roasted broccoli and quinoa. Drizzle any remaining marinade over the chicken if desired.
Serve warm and enjoy your nutritious, balanced lunch.