If you don't start learning to live below your means, you will be a slave to your stuff until your dying day. That doesn't mean not to buy good stuff, just have less stuff than you know you can comfortably afford.

That said, I didn't start getting a good cushion above sustenance until my mid-20's. Right now, I save about 30% of my salary into retirement, savings, and employee stock purchase plans. It took a while, but it's worth it. Driving a cheap car, not having cable, and living modestly translates into having a lot of freedom.

Coming home at night and knowing you have no debt is the best feeling in the world.