Despite being 76 years old, Arnold Schwarzenegger shows no signs of stopping.   The bodybuilding champion turned Hollywood star turned US politician, now in the ‘fourth act’ of his life, has reinvented himself into a motivator, and written a book, ‘Be Useful: Seven Tools for Life’, about guiding people to achieve a ‘happy, successful, useful life’, inspired by his singular American experience.   Today on Ways to Change the World, Arnold Schwarzenegger tells Krishnan Guru-Murthy how he can ‘be useful’, why world leaders are failing to resolve the Israel-Palestine conflict and why America needs a new candidate to enter the presidential race.   Produced by Silvia Maresca.