Way back when you first starting working, it probably felt like you had plenty of time to save for retirement. But now, years or decades later, you may be worried that your savings balance isn't growing fast enough. The good news is, whether you're 40, 50, or 60 years old, there are a few big changes you can make now to expedite the growth of your nest egg. Here are four of them.

1. Contribute more

Contributing more is an obvious move, but it's also the easiest strategy to dismiss. If you're of the mindset that you can't afford to increase your contributions, it's time to challenge that perspective. Here's why. You can either find a way to contribute more today or be forced into a serious lifestyle downgrade in retirement. Saving more today is always the easier option.

Couple reviewing finances together at home.

Image source: Getty Images.

Even small contribution increases can make a difference over time. The table below shows how much more you can save by increasing your contributions in amounts ranging from $50 to $500 each month. The numbers assume you are investing the additional contributions in the stock market to earn an average annual return of 6%.

Additional Monthly Contribution

Extra Savings After 5 Years

Extra Savings After 10 Years

Extra Savings After 15 Years

Extra Savings After 20 Years

$50

$3,573

$8,325

$14,736

$23,383

$100

$7,146

$16,652

$29,473

$46,766

$150

$10,720

$24,977

$44,209

$70,149

$250

$17,866

$41,629

$73,681

$116,915

$400

$25,587

$66,607

$117,890

$187,064

$500

$35,733

$83,259

$147,363

$233,830

Data source: Author calculations. 

Also, if you're making tax-deductible contributions to a 401(k), the extra savings will cost less than you think. Assuming you are a single filer making $50,000 annually, adjusting your 401(k) contribution from $200 monthly to $400 monthly only decreases your pay by about $160.

2. Take on slightly more risk

If you are invested conservatively today, you can also adjust your investment strategy to be slightly more aggressive for a shot at higher returns. Higher returns will build wealth faster, but there is a trade-off. You'll be taking on more risk, and that can backfire. For that reason, it's wise to be patient -- make only small, incremental changes.

An example would be slightly increasing the percentage of your portfolio that's invested in equities. You can use the Rule of 110 as a guideline for how much wiggle room you have here. Subtract your age from 110. According to the rule, the answer is the percentage of your portfolio to hold in equities if you have a moderate risk tolerance. At 50, for example, that equates to 60% equities, with the remainder in fixed income and cash.

3. Choose funds with lower fees

Mutual funds have operating and administration expenses that are passed on to shareholders. You'll see these expenses in the fund documentation as the expense ratio. A fund with an expense ratio of .2% will siphon 20 cents out of every $100 you invest to cover its costs.

Fund expense ratios can range from .015% to 2% or more. If you're currently invested in funds with expense ratios higher than .75%, you may be able to increase your returns by switching to similar but cheaper funds.

Index funds by Vanguard and Fidelity tend to have ultra-low expense ratios. Two examples are the Vanguard S&P 500 ETF (NYSEMKT:VOO), with an expense ratio of .03%, and the Fidelity 500 Index Fund (NASDAQMUTFUND:FXAIX), with an expense ratio of .015%.

4. Invest outside your 401(k)

The fees you pay to your 401(k) plan may also be limiting the growth of your retirement savings. Check your 401(k) statements or ask your benefits administrator to clarify your plan administration fees.

While it's not unusual for a small company to charge 401(k) administration fees of 1.5% or more, those fees do limit your growth potential -- particularly when they're on top of high mutual fund fees. If you're absorbing mutual fund fees of 1% and plan fees of 1.5%, you'll have a hard time achieving market-level growth no matter how you're invested.

Your alternative is to invest some of your money elsewhere. Contribute enough to your workplace plan to max out any employer matching contributions, but consider saving additional amounts to an IRA or a taxable brokerage account. In a standard brokerage account, you will incur taxes annually on interest, dividends, and realized capital gains. But you can manage around that somewhat by holding tax-efficient funds and stock in companies that don't pay dividends.

Save and invest more

The speed at which you build your retirement savings is a function of how much you contribute and your rate of return after fees. Grow your savings faster by getting creative with your budget to increase your contributions, optimizing your holdings for better returns, and minimizing the fees you pay to mutual funds and your 401(k). Beyond that, your best strategy is to wait for your money to grow into a nest egg that's big enough to fund your retirement.