Complex sentence: Since Oprah Winfrey exposed the world to The Secret in 2007, many celebrities endorsed the use of creative visualization and claimed it had a significant role in their success including Tiger Woods, Arnold Schwarzenegger and others.
Split into simpler sentences: Since Oprah Winfrey exposed the world to The Secret in 2007. Many celebrities endorsed the use of creative visualization and claimed it had a significant role in their success including Tiger Woods, Arnold Schwarzenegger and others.