Though Social Security will provide today's workers with some amount of income in retirement, those benefits generally won't be enough to sustain seniors by themselves. If you're an average earner, you can expect your Social Security income to replace roughly 40% of your previous income. Now that might seem like a decent chunk of money, but actually, most retirees need more like 70% to 80% of their former earnings to maintain a comfortable lifestyle, which explains why it's important for workers to build savings of their own.

But unfortunately, nearly half of Americans are lacking in this regard. Only 55% of workers today think they're doing an adequate job of socking away funds for their golden years, according to the 2019 Wells Fargo Retirement study. If your savings aren't up to snuff, here are a few critical moves to make immediately.

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1. Assess your spending, and cut back

Some people really do live paycheck to paycheck and use every dollar they earn to pay for basic necessities. But if you're spending any amount of money on non-essentials, whether it's vacations, restaurant meals, streaming services, or rideshares, and your retirement savings aren't as robust as they should be, then it's time to rethink your habits and start making changes.

You can start by setting up a budget to actually see where your money tends to go month after month. From there, you can review your different spending categories and determine which you're willing to cut back on. Maybe you'll cancel cable, or downgrade your cellphone plan. Or maybe you'll make more drastic changes, like downsizing to a smaller home to cut back on rent. The choice is yours, but know this: If you're really behind on building a nest egg, buying a few less coffees each week isn't going to cut it. Rather, you'll need to think about bigger changes to give your IRA or 401(k) the boost it needs.

2. Consider a second source of income

Cutting back on too many luxuries is apt to make you miserable, thereby putting you at risk of giving up on your savings efforts and compromising your future. Therefore, while it's a good idea to curb your spending to some degree to boost your nest egg, another smart bet is to look into getting a second job on top of your main one.

These days, side hustles are extremely common, and since the money you earn from one won't be earmarked for living expenses, you can use all of it (minus what you owe in taxes) to pad your IRA or 401(k). Best of all, that second gig can be something you actually enjoy doing. If you like music, teach an instrument you play. If you're an avid baker, sell your homemade goods at local markets. And if you love animals, sign up to pet-sit or walk dogs in your spare time. Over time, your side earnings could add up to a nice retirement plan contribution.

3. Invest your savings wisely

One reason you may feel you're behind on retirement savings is that you're investing your nest egg too conservatively. If you mostly limit yourself to safer investments like bonds, you're apt to grow your savings much more slowly than more aggressive investments like stocks allow for. But over time, the difference between the two could be huge.

Imagine you save $300 a month for retirement over a 35-year period. If you load up on stocks in your IRA or 401(k) and generate an average annual 7% return as a result (which is a few percentage points below the stock market's average), you'll wind up with about $498,000. But if you stick mostly with bonds and earn a 3% return during that window, you'll only grow your savings to about $218,000.

The takeaway? Don't play it too safe with your savings, especially if you have a lengthy window of time to work with. Investing more aggressively could also help compensate for the fact that your monthly retirement plan contributions may be on the smaller side. Or, to put it another way, sticking with safe investments means you'll have to put in a lot more money out of pocket to build enough wealth to retire comfortably.

If you're not pleased with your level of retirement savings, you should know that the sooner you make positive changes, the less stressed about the future you're likely to be. Remember, too, that as retirement nears, you should assess not only your IRA or 401(k) balance, but also your anticipated living costs to make sure the numbers line up. That way, you'll be better equipped to decide whether you're actually ready to leave the workforce, or whether you'll need to extend your career and boost your savings even more.