The principle of non-possessiveness, refers to the ability to let go. It encourages non-grasping, non-clinging, and non-attachment to possessions or even thoughts. Aparigraha teaches you not to fill your life with "stuff" (including extraneous worries!), but rather to take it easy and be happy with what you have.
This year, actually this month, I am turning thirty. You know, the big 3-0.
To some of my friends, this has been a huge deal and even a little depressing. I can't tell you how often I have heard someone sincerely say, "I'm getting so old."
I know. I roll my eyes, too.