John was very interested in Ecology and creating a sustainable future for the environment. He was also interested in planetary hunger and world peace and promoted these ideas long before environmental issues were an accepted thing.
John Denver and Tom Crum founded theWindstar Foundation located in Snowmass, Colorado. John also founded an organization called Plant-It 2020 which is dedicated to planting as many trees as possible by the year 2020. John was also instrumental in starting The Hunger Project. He also served on the board of directors of a number of other environmental organizations.