Place chopped walnuts in a 325 degree oven for 3-5mins or until roasted a deep brown. In a medium sized mixing bowl, cut the chicken breast into small/medium chunks, then stir in the onion, grapes, cranberries, apple and walnuts into the bowl with the chicken. In a seperate bowl mix together the mayonnaise, yogurt and lemon juice then gradually add this mixture into the bowl with chicken and other ingredients(more or less depending on how creamy you like your chicken salad) Ready to eat or refrigerate for later. ENJOY!!!!