David Mackay (Physicist and author of Sustainable Energy - without the hot air http://www.withouthotair.com/Contents.html):

'Have no illusions. To achieve our goal of getting off fossil fuels, these reductions in demand and increases in supply must be big. Don’t be distracted by the myth that “every little helps.” If everyone does a little, we’ll achieve only a little. We must do a lot. What’s required are big changes in demand and in supply.'