Zeinab Badawi talks to ecologist and environmental activist John Francis and asks, how far will people go for their green principles? After witnessing a massive oil spill in San Francisco Bay in 1971 when two tankers collided, Francis was so shocked he gave up all motorised transport for 22 years. He also stopped talking for nearly two decades and walked across the entire United States and much of South America to inspire others about environmental issues. Was it worth it?