People who lead with enthusiasm are people who want to be where they are. They are knowledgeable about the subject. When these people show their excitement, it gets all of their people as excited.
Ray Lewis was known for his motivational speeches before every game in his career. During his last season, where he won the Super Bowl, he was no longer an elite player but was kept in the line up due to his mental and emotional presence.
Oprah is a very popular person. She is known for helping out lots of charities and organizations. Because of her reputation, when she wants to help a specific organization, she can get lots of others on board with her.
Muhammad Ali -- Cassius Clay
Ali was known for being enthusiastic before and after his fights. He was loved by the media for always cracking jokes ad being open to them. He was feared by his opponents for being the best heavyweight fighter of all time.
The first President of the United States was not scared to be in battle. He lead his country, and his soldiers, with enthusiasm. He wanted to fight for what he believed in. He did not want to back down and he got his troops to rally behind him.