Walt Disney had a very clear sense of why. He was about happiness. Remember when Disney was founded, it was during war. People said that life sucked. And he said, "No." He was an eternal optimist who said: "Life is beautiful. It's about giving. It's about family." Look what happened. His cause grew and people committed themselves to helping him grow the Disney why and it was hugely successful.
During World War II, the pilot losses were staggering. In some bombing raids, as many as 80% of the planes that left did not return.
In the 1980s America reacted to the Soviet Union's invasion of Afghanistan. We supported a war that left a nation torn to pieces. And as the last Soviet tank left the country, so did we.