Billy Mills

In addition to his own speaking work, Mills is also the national spokesperson for Running Strong for American Indian Youth, a charitable organization that helps poor Native American people meet their needs for food, health care, clothing, water, and shelter, and teaches them how they can become self-sufficient and take pride in their heritage. In addition, the organization sponsors young Native American runners and encourages them to succeed. On the Running Strong for American Indian Youth Web page, an article about Mills explained, "In Lakota culture, someone who has achieved success would have a 'giveaway' to thank the support system of family and friends who helped him achieve his goal. Billy's work with Running Strong is his way of giving something back to American Indian people." In People, a reporter quoted Mills as saying, "I've designed my life so that I can continue to give."

In addition to his work as a speaker, Mills teamed up with writer Nicholas Sparks to write Wokini: A Lakota Journey to Happiness and Understanding. In the book, which is a parable of a young man's spiritual journey, a young man is given a mysterious scroll by his father after his sister dies. Through the teachings in the scroll, he learns to move through his grief and pain and find happiness and spiritual insight. In Booklist, reviewer Pat Monaghan called it "an optimistic book likely to appeal widely." By 2002, the book had gone through four printings.