A former addict who has become a personal trainer is hoping to change the lives of other addicts by encouraging them to focus on exercise and living a healthy, positive lifestyle.Doug Bopst's story is not unlike most former drug addicts': he started using drugs when he was a teenager, then moved on to selling them. He was depressed, suicidal and his habit was costing him hundreds of dollars per day. But when he was arrested for possession and put in jail, those 90 days behind bars turned out to be the best thing that could have happened to him.Watch the video above to learn more about Bopst's story and how he was able to change his life with the help of physical fitness.