Here is a major shift in the development of the plan that Jesus is implementing:

Until now, the disciples have been observers, followers, learners. Now they are going to become participants in the Kingdom.  They are moving  from classroom studies to being actively involved in implementing what they have been learning.

When the focus is on training and sending, one key ingredient can be overlooked: it is the receiving of authority and power. 

How did the disciples receive this authority? 
We can also be filled with the authority and the words of faith that Jesus gives.