Very. Summit day starts at the Crags Trailhead near 10,000 feet, climbs through Devil’s Playground to 14,115 feet, and covers about 14 miles round trip with 4,300 feet of elevation gain on a Class 2 trail (route details on 14ers.com). It’s one of five full days of program. Monday is an acclimatization day of hiking around camp and up Blue Mountain, but participants should train for months before they arrive, not just the week before. See what summit day takes. Talk with your health care provider about the hike and the altitude at the physical.