But many cited unexpected twists and turns of family life. More than a third had ended up supporting a child or grandchild, or paying for relatives' education. A fifth had taken on additional expenses caring for an aging family member, or had taken time off to raise children.
Business failures, job loss, emergency home repairs and health problems had affected more than half of the respondents. Nearly 20 percent had to start collecting early Social Security (lowering the amount of their monthly check). In all, Ameriprise's report identified 21 kinds of unexpected event, which it terms "derailers."
Many respondents were derailed more than once, and the total amount they lost grew each time. Those who took five or more hits averaged a total retirement account deficit of $144,000.
As rough as the past few years have been for many, financial detours shouldn't take us by surprise, according to financial planners.
"Some of these derailers are unique to our times, but most have always been there," said Suzanna de Baca, vice president of wealth strategies at Ameriprise.
(Read More: Don't Let 'Dead' 401(k)s Skew Your Retirement Portfolio)
De Baca did acknowledge that certain threats to a secure financial future have been "dialed up" in recent years. While market volatility has always existed, she said, more Americans than ever before are invested in stocks. And though not everyone had a pension in the 20th century, traditional defined-benefit plans have largely collapsed in this one.
"The biggest change to account for in our retirement planning is our longevity and the soaring cost of health-care coverage," de Baca said.
Yet Ameriprise found that Americans often are surprised by their financial ups and downs, and respond with a big dose of denial. Only a third of those who experienced a setback say their ability to afford the essentials in retirement will be seriously affected.
"It's great to see can-do attitude, but they are not doing the math," de Baca said.
That's not to say that the accidents of life have to upset our retirement plans completely, as long as we're willing to make adjustments. "You may not like all the choices, but there are still the choices," she said.
The choices boil down to three: spend less, save more or work longer.
For many approaching retirement age, working longer is not an option, and saving more for the few years before quitting will yield only a few more disposable dollars. For this group, De Baca recommends looking deeply at even essential expenditures, including mortgage and car payments. Explore downsizing to a smaller home or moving in with family members. Then give your retirement plans the same shakedown: Scale back on travel, or what you were going to spend on your retirement home.
How long it takes to recoup your lost savings depends on how much you're willing to compromise and on your income before retirement, though the study found that higher earners tended to suffer steeper life-related losses.
Those who have more time before retirement must make adjustments, too, mostly under the "expect the unexpected" heading. This can be accomplished by building a bit of cushion into your retirement saving goal: Ameriprise's study suggests $120,000 to $180,000, depending on present assets.
Maybe more importantly, consider what impact life events have on your retirement goals. When you lose your job or have a disabling injury, or your kid gets into that pricey private college, you may be consumed with how you're going to make ends meet. Remember that what appears to be a short-term problem is, at least financially, also a long-term one.