If using roasted chicken breast, place chicken in a microwave-safe bowl and microwave until warm, 1-2 minutes. Add to salad and toss.
If using whole chicken breasts, pat dry, and season both sides with pinch salt and a pinch pepper. Place a medium non-stick pan over medium heat and add 1 tsp. olive oil. Add chicken to hot pan, and cook until browned and chicken reaches a minimum internal temperature, 5-7 minutes per side. Slice into 1/4" pieces and serve on salad.