I see the biggest personal transformations in the clients that I am able to work with over long periods of time (6 months plus, about once a month). It is incredibly rewarding both for the client and myself.
This morning during our organizing session one of my long term clients proudly (and rightfully so!) told me about her practice of what I like to call the "one in, one out" rule. She had purchased new drinking glasses and while the new ones were in the dishwasher, she promptly (utilizing the "do it now rule") sorted out the old glasses for donating or recycling. This is something really simple, but something she probably would not have done in the past. Hurray!
If you are ready to let go of some of your old stuff, here's a great general guide to clearing out clutter.