Preheat a grill to medium high heat. Brush both sides of the pounded chicken breast with olive oil and sprinkle with salt and pepper. Grill on one side for 4 minutes, flip, brush the grilled sides with BBQ sauce, then grill the other side for 3-4 minutes, until the chicken is cooked through. Remove to a serving plate and brush the other grilled side with BBQ sauce. Cover and let rest for 5 minutes, then chop into bite-sized pieces.