Add the olive oil to a medium skillet over medium heat. Add the chicken and saute, stirring occasionally, until the chicken is cooked through. If the chicken sticks to the skillet, add a tablespoon or so of water to the pan. Transfer the cooked chicken to a bowl and let cool for 5 minutes.
Meanwhile, in a separate bowl, combine the cottage cheese, green onions, parsley, lemon juice, mustard, and garlic powder. Mix well and set aside.
Add the diced celery and the cottage cheese mixture to the bowl containing the chicken and mix well to coat all ingredients. Add salt and pepper to taste.