Boil chicken until cooked thoroughly. Allow to cool and then shred chicken.
Dice apples into pieces, chop celery stalks into small pieces, and chop walnuts if not already chopped.
Add shredded chicken, apples, celery and walnuts to a bowl. Add in mayo and stir to coat. Add salt and pepper to taste. I used approximately 1/4 teaspoon salt and 1/8 teaspoon freshly ground pepper.
Return to fridge to cool for at least one hour before serving. Store in fridge covered for 2-3 days.
Notes
Nutrition Facts (per serving, recipe makes 4 servings): 431 calories, 35 g fat, 15 g carbs, 3 g fiber, 23 g protein