FOR THE CHICKEN: In a gallon-sized ziplock bag, combine the chicken, 1/4 cup of the olive oil, the garlic, lemon juice, vinegar, and oregano; season with salt and pepper. Marinate the chicken in refrigerator for at least 20 minutes or up to 1 hour, turning the bag occasionally. Drain the chicken and discard the marinade.
Heat the remaining 2 tablespoons olive oil in a large skillet over medium-high heat. Add the chicken and cook, flipping once, until cooked through, 3 to 4 minutes per side. Let cool before dicing into bite-size pieces.
Cook the rice in a large saucepan with 2 cups water according to the package instructions.
Divide the rice and chicken into meal prep containers. Will keep covered in the refrigerator up to 3 days.