I just finished a great book by Joshua Becker called Clutterfree with Kids. Here are my favorite thoughts...
"Since deciding to live with less, I have less clutter in my home, less stress in my life, more time for my family, more generosity in my spending, more energy for my passions, more contentment in my heart, more gratitude in my soul, and far more opportunity to pursue things of greater worth...
Why would I want what everyone else has when they all want what I already possess?"
Also, a couple of people he quotes in the book:
"Comparison is the thief of joy." - Theodore Roosevelt
"Simplicity, clarity, singleness: These are the attributes that give our lives power and vividness and joy." -Richard Holloway
I don't feel like I have any thoughts of my own to add that could contribute much to that. SO well said already. Plus it's late and I'm tired :)