have the biggest heart

To be extremely kind, selfless, empathetic, and compassionate. My sister has the biggest heart of anyone I know. She's always volunteering at soup kitchens and trying to help the less fortunate. My sweet little girl will run up to crying kids on the playground to console them. She has the absolute biggest heart. It's the story of a young boy who has the biggest heart and is singularly focused on improving the lives of those around him.