Hope (concept)

Explanation
Hope is a common cliche in stories when heroes can't do anything.It's usually a last resort and a thing of chance.

Examples
When a hero is fighting a villain more powerful than them and they are losing they need hope.

When they are trying to prevent a terrible thing from occuring like a bomb exploding with low chances of success they need hope.

When they're at their last dying breath trying their best to fight it they need hope.