Cut the chicken breast into 1-inch cubes and place them in a medium bowl.
Chop the red bell pepper, zucchini, and red onion into bite-sized pieces roughly the same size as the chicken.
In a small jar, whisk together the olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Pour the marinade over the chicken and vegetables, tossing well to ensure everything is evenly coated.
Thread the chicken and vegetables onto skewers, alternating between the protein and the colorful produce.
Preheat a grill or grill pan over medium-high heat and lightly grease the surface.
Grill the skewers for 10-12 minutes, turning occasionally, until the chicken is cooked through and the vegetables have a light char.