Saving for retirement is a long-term proposition, and we only get one chance to get it right. And the consequences of what you’re doing or not doing to prepare for your golden years may only become clear in rare moments—or worse, once it’s too late.

One of my long-term associates shared the following story of one such moment which goes to show how easy it is for even someone very close to the retirement business to forget why Americans cannot just “save their way” to retirement.

My wife just changed jobs mid-year, and her HR department needed to know how much she had contributed already to her old employer’s 401(k) to make sure she would not go over federal limits when setting up her new one.

“What’s the most I can put in?” she asked me. “I think I’ve only contributed a few thousand so far, so I should be OK, right?”

I told her the max contribution at her age was $17,000 a year.

“That’s all I can contribute?” she cried, “How is anyone supposed to retire?” She thought for a second and said, “What is that, like $500,000 we’re allowed to save in my 401(k) over a forty-year career?”

“Now you know what I spend my time reminding people of every day,” I told her. “Of course you have to put money into your accounts, but you also must make sure that the money grows sufficiently. Saving even the max allowed may not add up to what many people will ultimately need.”

I have to say, Kevin–even though I’ve worked for you for over ten years, I think this was the first real light bulb moment for my wife. Before this, it had never dawned on her how necessary it is to grow our savings unless we want to severely reduce our lifestyle in retirement.

For my associate’s wife, it took this event to get her to do the math and realize how essential account growth is to success in retirement savings.

So have you had your “ah-ha” moment yet? If not, we suggest you begin with the end in mind: How long do you want your money to last once you retire? What type of lifestyle would you like to have? Once you have answered those questions, use our Excel Retirement Outlook calculator to see if your savings and current growth rates will help you reach your goals.