Source: Flickr user lemonjenny.

According to the Federal Reserve, nearly 50% of all working families haven't set aside any money for retirement, and many of the people who have saved are likely to come up short of their savings goals for retirement. One big reason that millions of Americans have put off saving money for retirement is that money is too tight. However, following these three suggestions from our Motley Fool analysts could make it easier to stick to your investment goals and achieve financial security.

Matt Frankel
One of the best ways to remain disciplined with your money is to make sure your budget is clearly defined and, more importantly, realistic. In other words, set clear goals and don't make your saving and spending plans so restrictive that you'll never follow through with them.

A study on New Year's resolutions found that people who set explicit (i.e., specific) goals for themselves were 10 times more likely to be successful. For example, "I want to go out to restaurants less" is a goal that's destined to fail. However, "I'm only going to eat out one time per week" is specific and therefore simpler to achieve.

When budgeting for things like grocery shopping, gas, and recurring bills like electricity, make sure you budget for the actual costs of each. For example, if the cheapest electric bill you've ever gotten is $80, then budgeting $80 for electricity each month is unrealistic. If you spend $25 in gas per week on your work commute alone, then budget a little extra.

When making a budget, it's important to leave yourself the flexibility to treat yourself a little while still spending and saving responsibly. 

An easy way to improve your discipline with money is to deposit a set percentage of your salary (after 401k and IRA contributions) into a savings account monthly. Many banks let customers set up automatic monthly transfers from checking to savings accounts.

To complement that plan, try to use only debit cards, checks, and cash throughout the month, as this forces you to balance your budget monthly without accumulating more debt or dipping into savings. This should give you a better idea of where to reduce expenses -- e.g., your smartphone, cable, grocery, or insurance bills.

To understand why you should improve your savings and credit card debt, consider these sobering numbers. According to Forbes, people who start saving 10% to 15% of their annual income between the ages of 20 to 25 could possibly retire in their 60s. But those who wait until age 40 to start saving would generally have to save a whopping 43% of their income to retire in their 60s. Meanwhile, the Federal Reserve reports that average credit card debt per American household hit $7,283 in 2014. According to CardHub, that figure is roughly $1,000 below the "tipping point" at which minimum payments become unsustainable.

Therefore it makes sense to set up an automatic savings plan and reduce your dependence on credit cards as soon as possible.

Dan Dzombak
There are also psychological ways to develop good saving habits. For example, another reason it's best to use cash instead of plastic is that it's easy not to realize how much money you are spending when using a credit card or debit card. Multiple studies have shown that people who use credit cards spend more, are more likely to forget how much they spent on purchases, and are willing to pay more for the same item than those using cash.

The act of handing someone physical bills from your wallet or purse makes you think a lot more about the purchase. It's important that you actually see the money; when you charge an item, your brain doesn't internalize the spending and only sees the reward of your purchase.

Further studies in this area have shown that people are less likely to spend larger bills. This is called the "denomination effect." For example, you are less likely to spend a $50 bill than you are to spend five $10 bills. So instead of leaving the house with a credit card, consider heading out with some $100s and see how much you spend.

Dan Caplinger
One of the biggest challenges in dealing with your financial goals is that it can be hard to keep track of all of them. Nearly everyone has to plan for their retirement at the same time that they consider more immediate wishes like buying a home or planning their next vacation. Those with children also have to take on the obligations of educational expenses, and many people want to leave legacies for their families after they pass away. It can be hard to keep all those goals organized and stay on track.

A great way to stay disciplined is to have different accounts for each of your goals. Often, that's the best move anyway, as different types of tax-favored accounts are aimed at retirement, educational expenses, and healthcare expenses. But even for expenses like down payments on homes, for which case tax-advantaged accounts aren't available, setting up a separate investment account for each discrete need makes it far easier to keep track of where you stand and how much more you have to save to reach your goals. Some brokers even allow you to create subaccounts within a specific account, separating out goal-tracking while keeping statements and tax forms under control. Having a handle on each of your goals will do wonders to improve your investment discipline.