Get up close with four presidents of the United States discussing some of their most personal causes.

Former President Jimmy Carter sits down with Jon Stewart to explain his efforts to eradicate the harmful Guinea Worm. Former President Bill Clinton talks about his foundation's campaign to combat ebola. President Barack Obama joins Trevor Noah to unpack how to be authentic amidst the demands of the presidency. Then Senator Joe Biden talks to Jon about how he would approach the presidency, and what it means to him.