I was a card-carrying member of Friends of the Earth, back in the 80s when I was still in school.  I'd attend conferences where we discussed the woes of indigenous people in the Indonesian jungles being exploited, the dangers of deforestation, acid rain, and of course, nuclear proliferation.  It was not fashionable to be a greenie during those days in Hong Kong, so it was lonely work sometimes. 

Fast forward twenty years: I now have a job, a house, and a car that I drive for an hour to work every day.  A few times a month I hop on a plane and help add another few tons of greenhouse gases to the atmosphere.  My annual carbon footprint is 22.273 tonnes, the majority of that from jet travel (14 tonnes).  According to the Carbon Footprint calculator, the worldwide average needs to reduce to 2 tonnes to combat climate change.

To help matters, I try to work from home at least twice a week (cutting the commute and also gaining two hours of extra productivity).  I drive a Honda SUV that I'm trading in for a hybrid next month.  I'm a pescatarian; we buy locally produced food whenever we can; I recycle as much as possible. I even use environmentally friendly insecticide at home. I try to combine business trips so I cover several countries in one trip.

Yet I still feel like a hypocrite.

It's the modern dilemma but there is no choice, we need to do whatever we can, in whatever small measures are possible.

You could say the only way I can avoid that guilt is if I go live in a cave, plant my own food and catch my own fish.  That would definitely reduce my carbon footprint to zero, because I'd die of starvation pretty quickly.