From a recent announcement about commemorating TNT's 20th year:
This participant thinks that sums it up quite nicely.
In 2008, Team In Training (TNT), the world’s largest sports endurance training program, will celebrate it’s twentieth year of saving lives, one mile at a time. The Leukemia & Lymphoma Society’s TNT provides coaching and support for people to cross the finish line at marathons, cycling and triathlon events. Participants raise funds as they train.
TNT participants say that changing your life, making lasting friendships with teammates and impacting the lives of thousands of blood cancer patients is what makes the experience so rewarding.