When you are invested in the Cub Scout Pack you make the Cub Scout Promise in front of the rest of the Pack and your Parents.  This means you are accepting the ideals of the Scout Movement and pledge that you will do your best to uphold them.

The Cub Scout Promise
I promise that I will do my best, to do my duty to
God and to the Queen, to help other people
And to keep the Cub Scout Law.

The Cub Scout Law 

Cubs Scouts always do their best and think of others before themselves and do a good turn everyday.