Lily Tomlin once said, "Even if you win the rat race you're still a rat!" Unfortunately, that's what most people are doing - trying to win the rat race. Why would people do that? Because they don't know the difference between income and assets.
Income is the money that your employer or business trades you for your time. Whenever you stop putting in time, your income also stops. Income is what keeps you in the rat race. Working for income also means that even if you have plenty of money you won't have time to enjoy it. Why? Because you'll be busy trying to make more income.
Now assets are completely different. Assets pay you whether you work or not. Assets, like real estate, stocks or businesses (that you don't personally work in) require you to invest time and effort up front, and then pay you after that. For instance, suppose you save up your hard-earned dollars and buy a piece of rental property. When you rent out that property, it pays you money even though you aren't putting in any time to earn that money.
The difference between the wealthy and the rats of this world is the difference between assets and income. If you want to be wealthy you have to develop assets. Otherwise you'll end up at the finish line and wonder why you're still a rat! For more info on assets check out these great resources:
Robert Kiyosaki's "Rich Dad, Poor Dad" series
Robert Allen's "Multiple Streams of Income"