A substantial minority of Americans are sure they will run out of money in retirement, according to a Northwestern Mutual study released Tuesday.

Fourteen percent say they will not have enough money to fund what will probably be a longer life span. At the same time 34 percent say there is a better than 50 percent chance they will end up with no money.

However, most are doing nothing to address this bleak financial future, according to Northwestern Mutual’s 2016 Planning & Progress Study. Only 21 percent say they have increased their savings, while 44 percent say they have done nothing at all, according to the survey of 2,646 Americans. At the same time, one quarter of respondents feel it is extremely unlikely that Social Security will be there when they are ready to retire.

“The prospect of an extended retirement in an environment of diminishing safety nets makes it even more essential that your financial plan is flexible enough to stretch as long as needed,” says Rebekah Barsch, vice president of planning for Northwestern Mutual.

For the second year in a row, health-care costs emerged as a top-cited obstacle to financial security in retirement, cited by 45 percent of respondents, along with a lack of savings, cited by 44 percent.

“Interestingly, though people recognize the impact of health-care costs and insufficient savings on retirement security, they are not necessarily seeing the role of financial planning as the connection between the two,” continues Barsch. “A solid financial strategy can ease both concerns.”

However, debt also is pressuring Americans, with 27 percent saying eliminating debt would have the biggest impact on their finances, while 26 percent say earning more money would be the most significant. Others selected a number of different issues that would help.

Forty-six percent of Americans expect their own finances to improve this year, but only 31 percent think the U.S. economy will improve.

“While it's encouraging to see that financial worries aren't putting a damper on the big picture for Americans, optimism without action is like an engine without fuel – it won't get you far,” concludes Barsch.