In sports, youth are coached to see persistence and hard work as important paths to personal improvement and success. They come to understand through practice that mistakes are tools to help them improve and that collaboration and teamwork are keys to success in team sports. These ideas about the importance of effort, persistence, mistakes, and collaboration are important components of a growth mindset, the belief that ability is not fixed but can be improved through effort. This paper describes a strategy of combining growth mindset principles, mathematics concepts, and sports examples to support students in shifting their mindsets about their own abilities. The authors share outcomes from implementing these activities at five out-of-school settings.