30 Days of Biking, whose fourth year begins April 1, has one rule: Bike somewhere every day for 30 days—around the block, 20 miles to work, whatever suits you—then share your adventures online. We advocate daily bicycling because we believe it enriches lives and preserves the Earth. A worldwide, thousands-strong community of joyful cyclists has been forming around that idea since April 2010—and will further amass in 2013! We ride our bikes every day.