If using roasted chicken breast, remove from packaging and microwave until warm, 1-2 minutes. Add to salad and combine.
If using chicken, pat dry and cut into 1" dice. Season with 1/4 tsp. salt and a pinch of pepper. Place a medium non-stick pan over medium-high heat and add 2 tsp. olive oil. Add chicken to hot pan and stir occasionally until chicken browns and reaches a minimum internal temperature of 165 degrees, 5-7 minutes. Add to salad as desired.