Something that already bothers me for quite a while is our massive waste we produce. Working in a printing company - even if it's just as an extra help - makes this feeling worse. When I applied for the college where I am studying now I had a lot of misprinted A3 sheets. I collect one-sided-used paper since years to use them for scribbling or studying, taking notes and so on. But I figured out I prefer writing on proper books rather than loose sheets. Because bookbinding is a big passion I decided to do some recycling notebooks, one in size A4 and two in size A5. 
The cardboards are reused and the cover of one of the A5 notebooks is even one of the works I did for the application, my bucket list. So it has even a third use :)