Ride the Alaska Ferry from Seattle to AK
Hike some portion of the Pacific Crest trail
Raft the Colorado River
Build my own electric trike (tadpole configuration, though)
Fly in a hot-air balloon
Around the world on a cargo ship
Other pinner says: "Renting a glass igloo in Finland to sleep under the northern lights. Must do this!" I agree!
Hike some portion of the Appalachian Trail
Write a complete novel, no matter how crappy it ends up being
Schedules for beginner runners!