Will I be ready for the Grand Canyon - UPDATE

In May I'll be joining a small group to walk 24 miles across the Grand Canyon (Grand Canyon Rim to Rim) in one day. In addition to the 24 miles, the crossing starts with about 6,000 feet of descent and ends with about 5,000 feet or ascent. I recorded this video in what I thought was winter's last gasp; as it turned out, we had an amazing "bonus" late March snowstorm, and I got some great ski days in after all!!