Preheat your grill or grill pan to medium-high heat.
In a small bowl, combine lemon juice, olive oil, garlic powder, salt, and pepper. Mix well to create a marinade.
Pat the chicken breast dry and then brush both sides with the lemon marinade.
Place the chicken on the grill and cook for approximately 6-7 minutes on each side or until the internal temperature reaches 165°F.
While the chicken is grilling, rinse the quinoa under cold water. In a small pot, combine the rinsed quinoa with water (use a 2:1 water-to-quinoa ratio) and a pinch of salt. Bring to a boil, then reduce heat to simmer, cover, and cook for about 15 minutes until water is absorbed and quinoa is fluffy.
Steam the broccoli by placing it in a steamer basket over boiling water for approximately 4-5 minutes until tender yet crisp.
Plate the grilled chicken breast with a serving of quinoa and steamed broccoli. Drizzle any remaining lemon marinade over the chicken for extra flavor.
Serve warm and enjoy your balanced, nutritious lunch.