Do Your Best is the Cub Scout motto. It is one of the most important things for the Cub Scout to learn. Often he becomes so interested in winning that he fails to see the importance of doing the best he can at everything.
One boys best might be quite different from another boy's best. Help the boys see that no one can find fault with them if they always do their best in everything they tackle. As a leader, you can see that the Cub Scout Promise, the Law of the Pack, and the Cub Scout motto are related to everything a Cub Scout does. These are not just tests to be passed in order to qualify for induction. Take advantage of every opportunity to mention how the Promise, Law, and motto fit an activity or service project in which the boys are involved. Help them see this is a good way to live.
In another part of the CS Leader book it defines the part of the Cub Scout promise;
To Do My Best. Your best is not the same as someone else's best. Try to beat your own record, rather than merely trying to do better than someone else. It makes you feel good to do your best.