I saw a great demonstration done at a Regional Workshop. 

Sister Myers had a Bishop come up and put his hands out. 
She had a pile of hymnbooks to represent his responsibilities. 
Everytime she said one of his responsibilities, she put a book in his hands. 
His arms started to get tired really fast. 
Then she had three Primary leaders (representing a presidency) come up and put their hands under his to help support the books (giving him support in his calling) 
The load was much easier to bear and together they could take on more books.(responsibilities).

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This could be switched to where the children could come up and be the supports and tell what they could do to support (sustain) whomever you have being the church leader.
Things that they could do could be ~ help keep the buildings clean, be an example and a missionary to others, prepare to now to some day enter the temple, help in Primary when asked, etc... (Dana H)