Prepare the Chicken: Cook the chicken breasts until fully cooked. Let cool. Finely chop or shred the chicken.
Mix the Salad: In a large bowl, combine the mashed avocado and Greek yogurt (or mayonnaise) until smooth. Add in the lime juice, chopped chicken, red onion, celery, and optional herbs. Mix until well combined. Season with salt and pepper.
Serve or Store: Serve immediately, or divide into portions and store in airtight containers in the refrigerator. Enjoy as is or spread onto soft whole-grain bread or wraps for a more filling snack.