It’s a cautionary tale for working people: retirees aren't always so happy in their golden years.

In a new survey, 28 percent of seniors say it's worse than they expected.

What is it that these people say is tarnishing their golden years?

It's not their health or families that worry them -- it's their own lack of funds in retirement.

The top reason, by far, is financial worry -- the gap between Social Security and their savings and pensions.

But experts say money is perhaps the one factor that people can control the most – more so than health or longevity. They insist that people can steer toward financial security decades in advance.

It begins with having the discipline to make every payday -- for everybody, at every age – a process of “paying yourself first,” through payroll deduction into a retirement account.

The survey, which was done for Nationwide, found that 28 percent of seniors say life is "worse" than they expected. Of that group, 78 percent cited "income" as a reason ... and 76 percent blamed the "cost of living."

The study also suggested that unhappy retirees had overestimated how much they'd be getting in monthly Social Security benefits – and underestimated how much healthcare and other expenses would actually cost them.