Daughter is struggling with weight

My daughter (10 years old) has always been a big girl. She’s currently 4’11 and 170 lbs. Her father and I share custody, however I haven’t been in her life for years (total) on and off because of issues between her dad and I(not that I didn’t want to- he moved and refused to tell me where he moved to for years. I hired a PI to find my daughter). I gained full custody of her in November of 2023 and her father has been in and out of jail since. I recently learned that her great-grandparents were the primary caregivers whilst in her father’s care. They didn’t really do any kind of intervention to help her with her weight. They went out to eat 3x a day and let her do whatever she wanted. They suggested diet pills instead of actually putting in the work theirselves. She’s always had issues with her weight. She’s started a goal this year to lose 40lbs by December of 2025. I support her fully and made suggestions on how we can achieve her goal. She was so excited and embarrassed to admit this to me. She doesn’t want me to tell anyone, but everyone around her loves her unconditionally. I decided to keep this between us. We go on ‘secret’ 1 mile runs at 4AM with our dog every single morning. I bought a punching bag for her and myself and we use it right after our runs and after she gets off the bus from school. My husband doesn’t even know! We are ALL in therapy (5 people in the house)- individual and family therapy. She’s such a rockstar for sticking to this and I don’t want her to give up! She’s not interested in any sports activities (she feels like she’s too big). She’s very uninterested in a gym membership (for the same reason). How do I make a weight loss journey fun and engaging for my daughter?