Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Dice the chicken breast, sweet potato, and zucchini into uniform 1/2-inch cubes to ensure even roasting.
Place the chicken and vegetables on the prepared baking sheet, drizzle with olive oil, and sprinkle with salt, pepper, garlic powder, and oregano.
Roast in the oven for 18-20 minutes until the chicken is cooked through and the sweet potatoes are tender and golden.
While the tray roasts, bring 0.5 cup of water to a boil in a small saucepan, then stir in the dry couscous.
Remove the saucepan from heat, cover tightly, and let the couscous steam for 5 minutes before fluffing with a fork.
Transfer the fluffed couscous to a large bowl, add the roasted chicken and vegetables, and drizzle with fresh lemon juice before tossing gently.