Personally I try to live in a way that reduces waste (within reason) and I'm very faithful about recycling anything that can be recycled.
Professionally, I started out in graphic design where I was working on lots of printed (paper) goods: brochures, business cards, posters, billboards, folders, stationery, ads, etc. The design part of that process isn't very wasteful, but the actual printing process is unbelievably wasteful. I know trees are a renewable resource, and the 'wasted' paper can be recycled, but all that effort logging + papermaking + shipping + recycling is being wasted too when you throw away a bad print job, or a bad cut job, or an entire print run happened but the colours were slightly out of alignment so you have to reprint the whole run again, etc. The amount of wasted prints on any print job can easily equal, or surpass the number of good final prints by the time the whole process is over! (It's not supposed to, but it often happens anyway).
I didn't switch to doing web design because of the environmental toll of graphic design, but sure does make me feel much better to know that after I'm done my part designing something for the web now, the only 'resources' being used to display that design will be a little bit of electricity (in your device). I'm glad to not be involved with the waste of print design anymore :D