Place the chicken in the slow cooker and sprinkle with a pinch of salt and pepper. Pour the lemon juice over the chicken, which will help tenderize and brighten the flavor.
Cover and cook on low for about 3-4 hours until the chicken is completely tender and easily pulls apart with a fork.
Once cooked, shred the chicken into fibrous strands using two forks, and let it rest for a few minutes to cool slightly.
In a mixing bowl, combine the shredded chicken with mayonnaise, chopped celery, and finely chopped red onion. Mix thoroughly until well coated.
Add salt and pepper to taste, and sprinkle with optional paprika for a smoky flavor. Toss in chopped herbs if using, and stir everything together.
Serve the shredded chicken salad immediately or refrigerate for up to a day to let flavors meld. Enjoy it on its own, in a sandwich, or over greens for a quick, satisfying meal.