(CNN Money) — Remember that old Steve Martin joke about the secret formula for becoming a millionaire? “First, get a million dollars …” Okay, getting the odometer on your investment portfolio to click over into seven digits isn’t quite that easy. Only 7% of American households ever manage it, according to research firm Spectrem Group — though it’s certainly not for lack of desire. While $1 million may not be worth what it was back when Martin was a wild and crazy guy in the late ’70s, achieving that iconic number still has profound allure. It means that you’re ahead of the game. You’re assured a baseline retirement security. You’ve arrived. Martin may have oversimplified, but the reality is that getting your portfolio to the $1 million mark is not nearly as difficult as you may think, even if you’ve managed to put away only a fraction of that amount so far. You just have to understand how to operate the three basic levers of wealth building: how much time you have to work with, how much you save, and how you invest that savings.