Spray a skillet with cooking spray and heat over medium heat. Dice chicken.

Season chicken with salt and pepper to taste and cook in preheated skillet until no longer pink, stirring occasionally to avoid sticking. Set aside to cool while you prepare the remaining ingredients.

Dice apples and celery. Shred or chop lettuce.

In a medium bowl, whisk together the mayonnaise and lemon juice.

Stir in the apples, celery, walnuts, raisins, and chicken; serve over a bed of lettuce.