Spend some time deciding which basic principles you want the kids to learn about running and make sure these principles are woven into your sessions. No matter what kind of program you plan, kids need to learn to pace themselves. They need to be taught to start out slowly and pick up the pace only after running with a good steady rhythm, instead of going out as fast as they can at the start. Good sportsmanship is a quality of a true athlete. Great runners exhibit good sportsmanship.
Good sportsmanship includes cheering for and congratulating others.
It also includes not giving up. Having a personal goal can help you accomplish things. Goal setting can be incorporated into journal writing. Kids should be able to come up with reasonable goals for themselves or for the whole group. Running long distances develops over time.