Try to use only pastel or soft colored paper around the office. Use Post-it Notes that contain recycled materials. Avoid fax paper and other forms of carbon-copying paper. These are too hard to recycle and don't mix with white or colored paper. Try using e-mail to send purchase orders or confirmation letters.
Some toner cartridges come with pre-paid shipping forms for easy return.
Try putting a few plants up around the office and see how the mood changes for the better.