Darrow Kirkpatrick is an early-retired civil and software engineer with five decades of hiking, biking, and technical rock-climbing experience, including first ascents in the Shawangunks of New York and the sandstone belt of Tennessee. He climbed three big walls in Yosemite Valley, California: The Shield and The Nose on El Capitan, and The Regular Northwest Face of Half Dome. In 2011 he founded Can I Retire Yet? — winner of the 2019 Plutus award for Best Retirement Blog. His personal finance books include Retiring Sooner and Can I Retire Yet? In 2021 he completed a six-year section hike of the 500-mile-long Colorado Trail, the subject of his memoir, Two Sticks, One Path.