Retirement is supposed to be a relaxing time, when you can finally unwind and start living life on your own terms. For many people, though, it's exactly the opposite.

New research shows that millions of older Americans are barely scraping by in retirement. In fact, roughly half of adults over age 65 who are living alone can't afford to pay for their basic necessities, according to a recent study from the Center for Social and Demographic Research on Aging. Among couples, nearly one-quarter of households are financially insecure in retirement.

Going into retirement with a less-than-ideal nest egg can make your senior years much more difficult than they need to be. And the problem could get worse in the next couple of decades.

Senior couple looking at documents feeling worried

Image source: Getty Images.

Retirees may be over-relying on Social Security benefits

If you enter retirement with little to nothing squirreled away, chances are your savings will only last a few years. After that, you'll be left to any other sources of income you may have. With pensions becoming rarer for most workers, that means you may only have Social Security benefits to depend on.

The problem with that, however, is that Social Security benefits aren't designed to be your sole source of income in retirement. In fact, they're really only supposed to cover around 40% of your pre-retirement income. And considering the average check amounts to just $1,503 per month -- or just over $18,000 per year -- it may be challenging for many retirees to survive on Social Security alone.

Keep in mind, too, that in some cases you may need to pay taxes on your benefits. Although 37 states don't tax your monthly checks, a handful still do. In addition to state taxes, you may also be subject to federal taxes on your benefits -- which will make it even more difficult to survive on your monthly checks alone.

As if those facts aren't dismaying enough, the situation could get worse in the coming decades. The Social Security Administration is on shaky ground, and with so many baby boomers retiring and living longer lifespans, the program is paying out more in benefits than it's receiving from payroll taxes. To bridge the gap, the Social Security Administration has been pulling money from its trust funds so that retirees can still receive the entire benefit amount they were promised.

However, those trust funds are expected to run dry by 2035, at which point the only money available to pay out in benefits will be what comes in from taxes. And according to the Social Security Administration's latest estimates, tax money will only be enough to cover around 75% of expected benefits. That means that unless Congress figures out a solution before 2035, retirees may see their benefits slashed significantly. And if you're depending on that money just to make ends meet, those cuts could spell trouble.

How to boost your income in retirement

One of the best ways to create a more financially secure retirement is to increase your savings as much as possible. That's easier said than done, of course, but a little extra cash can go a long way. If your employer offers matching 401(k) contributions, take full advantage of them. That's essentially free money, and nobody wants to miss out on free money. You may need to make some financial sacrifices to stash more money in your 401(k) or IRA, too. These cuts may be tough, but just remember that if you don't make sacrifices now, you'll need to make sacrifices in retirement.

If you can swing it, working a few years longer can help as well. Working longer has a double bonus because not only does it give you more time to save, but when you're spending fewer years in retirement, you won't need as large of a nest egg. Although your retirement will be shorter, it may be worth it if it's also more comfortable financially.

Some people choose to forgo the traditional retirement altogether, instead taking an "unretirement" approach. Just over 60% of workers currently in their 40s say they'd rather work on and off throughout their senior years rather than stopping work altogether, according to a survey from TD Ameritrade. If you choose to go this route, it could help your savings last much longer. Instead of stopping work completely and then spending the next few decades living off your savings (or Social Security checks), you could take a few years off work to relax, then go back to working part-time for a year or two, then take another couple of years off. This way, you still get to work less and enjoy more downtime, but you won't need to survive solely on your savings and Social Security benefits.

Another option to increase your retirement income is to delay claiming Social Security benefits. If you wait to claim until after your full retirement age (FRA) -- which is age 67 for those born in 1960 or later, or either 66 or 66 plus a few months for those born before 1960 -- you'll receive extra money each month for the rest of your life. If your FRA is 67 and you wait until age 70 to claim, for example, you'll receive your full benefit amount plus an additional 24% each month. If you have no choice but to survive only on your Social Security benefits, this money can go a long way. It can also create a cushion to protect your benefits in case there are cuts in the future.

Retirement can be a stressful period in your life if you're not financially prepared. The good news, though, is that the sooner you realize your savings are off track, the more time you have to make adjustments. And the more thought you put into your retirement plans, the more enjoyable your later years will be.