Once you know, why do we convince ourselves otherwise?

I have gone back and been reading my old sustainability books.  The Ecology of Commerce by Paul Hawken, Confessions of a Radical Industrialist by Ray Anderson, and others.  And I read their observations on our impacts of business and human existence on the planet and am shocked by what we are doing.
But I have read these books before, I knew these impacts years ago, why does it keep shocking me?  I think in part because of the life I live I am quite removed from the visual impact of 2,562 tons of solid waste in a year from one company.  There are thousands of companies across the world, of course of various sizes, but we don't see all of the numbers added up together in daily life.

So while I know that driving my car, using water, gas, and creating waste are things I do on a small scale every day - what if I were to see this as a sum?  All totalled up would I see my impact differently and make the needed changes?
I think this would help dramatically - as I don't think it is a big deal to use my little Toyota Matrix every day for trips under 20 miles.  Heck it isn't like I am commuting 60 miles in an SUV?  But that there is the piece we have to be wary of, we can justify ourselves of anything.  And guess what - my lifestyle, my consumption, the waste I generate all have a place in that adding up of the world's impact.

What activists are trying to get at, is for ALL of us to think about the details of our impacts and make improvements.  It isn't about doing less so others can do more... it is about taking that responsibility and saying my life is adding to a really big number of global impacts and what can I do to lessen that.