Minimalism

We buy a number of stuff that we will probably never really need and while we live in houses over 3 times larger on average than 50 years ago, we do so we can store all of that stuff. Clean air should be the main thing filling up empty space at your place; not your stuff. This goes further as a life philosophy. Less stuff leads to less stress and more free time to do whatever one finds fun. Be mindful of what you buy. Live simple, live free.

Environment

Our willpower has been proven to be limited but we do only have access to 1 planet we can call home. So why not give more thought as to preserving it? Most of the time this benefits every party involved. Quick example: 50 pages printed on one side of a piece of paper, can be reduced to half the thickness by printing it two-sided. This will also reduce cost - both for printing and storage - to half, so why print only on one side of paper? Though Zero Waste is extremely hard to achieve, all of us can certainly cut back somewhere and become less harmful to our planet. Small things combined can have dramatic effects. You can read more about Zero Waste here (via Reddit!).