A well-designed summer challenge does three things at once: holds member attendance through the seasonal dip, drives referrals through challenge buddies, and creates content for social media. The challenges that work in 2026 are 6 to 8 weeks long, have a clear theme, include both fitness and community goals, and have a tangible reward at the end. This guide covers four challenge formats that work, how to price them, and the common mistakes that turn challenges into burdens.