In a large bowl, combine all ingredients for meatballs, set aside.
Heat oil in the pot. Add onion, carrots and celery. Cook, stirring occasionally, until tender, about 3 minutes. Stir in garlic, thyme and cumin until fragrant, about 1 minute.
Add chicken stock and bay leaf. Bring to a simmer.
Wet your hands to keep ground chicken from sticking. Form golf ball-sized meatballs, about 2 tablespoons each and gently drop them into the pot.
Simmer meatballs for 20 minutes. Add zucchini noodles, spinach, and lemon juice. Simmer another 2 minutes until noodles and spinach are just tender.