Heat olive oil or butter in a large pot over medium heat.
Add garlic and celery and sauté for two to three minutes until fragrant.
Add the chicken and cook for three to four minutes to lightly seal the outside.
Pour in the chicken broth and bring to a gentle simmer.
Cook for about fifteen minutes until the chicken is fully cooked and tender.
Remove the chicken, shred it, then return it to the pot.
Add zucchini and spinach and simmer for three to five minutes until just tender.
Season with salt, black pepper, and dried herbs, stir well, and serve hot.