Money is the top source of stress among Americans, according to a survey from Northwestern Mutual, and nearly nine in 10 survey respondents said there's nothing that makes them happier than knowing their finances are in order.

Saving money isn't easy, though, no matter how much you're earning. There are always bills to pay, and when you have leftover money at the end of the month, it's much more fun to splurge on something you don't need than to stick it in your savings account or retirement fund. Especially when retirement is still decades away, it can be tempting to push saving to another day -- but wait too long, and it will be nearly impossible to catch up.

Fortunately, saving for the future doesn't have to be stressful. By making a few lifestyle changes and adopting some simple habits, you can save more money and ensure your finances are in tip-top shape.

Dollar bill folded into upward arrow

Image source: Getty Images

1. Write down your financial goals

It's one thing to have a goal in mind, but it's another to actually write your goal down. In fact, writing down your goals has been scientifically proven to help you achieve them.

In a study performed by researchers at the Dominican University of California, one group of participants was asked to simply think about a goal, while another group was asked to write down their goal, create an action plan for achieving it, and send a weekly progress report to a friend. The results? Within the first group, only 43% of people either achieved or made significant progress toward reaching their goal. But a whopping 76% of those in the second group reached or came close to reaching their goals.

Writing down your goals and creating a specific plan for how to reach them not only holds you accountable, but it also provides a roadmap to guide you along your saving journey. For example, if you're saving for retirement, you may have a big goal in mind for how much you want to save by the time you retire. But it may also be helpful to have smaller, less intimidating goals along the way to keep you on track and avoid getting discouraged.

2. Automate your savings

When you have to manually transfer your money from your checking account to your retirement fund or savings account, it's easy to forget to do it or spend the money elsewhere. But with automatic transfers, you can set up your bank account to transfer a certain amount every week or month, making saving effortless.

Once you have a saving goal in mind, set up your accounts so that you're automatically transferring the amount you want to save. You may even choose to set up multiple transfers for different goals. For instance, you may transfer a certain amount from each paycheck directly into your 401(k), while you also transfer money into a savings account to build an emergency fund. When you no longer have to manually move your money to different accounts, it streamlines the saving process.

It's even possible to automate your entire budget and remove much of the stress involved in managing your money. When your bills are paid automatically each month and you're also automating your savings, all you have to do is sit back and watch your savings grow over time.

3. Rethink how you prioritize your savings

A lot of people may choose to save only what they have left over at the end of the month. While that's better than saving nothing, a better approach is to think of your savings as if it's another bill you absolutely have to pay. The electric company won't cut you any slack if you simply decided you didn't feel like paying your bill one month, so think of your savings similarly.

If you aim to save a certain amount per month for retirement, do everything in your power to save that much every single month. It's easy to skip saving a few months because there aren't any major short-term consequences -- unlike if you were to stop paying your other bills. But the long-term consequences can be severe if you put off retirement saving. Once you skip one month of saving, you may get into a habit of skipping it whenever you feel like it. Then before you know it, you've reached retirement age and you're nowhere near the goal you set for yourself.

When setting any financial goal, make saving a top priority each month. Of course, you still have to pay your rent or mortgage and any other bills, but make sure you can still afford to save. If you find you don't have enough cash to cover your saving goal, you may need to make sacrifices. But these sacrifices will be worth it when you're able to retire comfortably and achieve your other financial goals.

4. Increase your retirement fund contributions on a regular basis

By automating your savings and transferring a set amount to your retirement fund every month, retirement planning becomes a "set it and forget it" task. That's good in a lot of ways, as it takes some of the stress out of the saving process. But it's still smart to increase your contributions whenever you can.

When you get a raise, for example, you may choose to bump up your retirement savings slightly. Or if you receive a bonus, it might be a good idea to put at least part of that money toward your savings. These adjustments don't need to be major -- the idea is to simply keep your savings on an upward trajectory.

One easy way to ensure you're consistently saving more for retirement is to contribute a certain percentage of your income to your retirement fund. Then whenever your income increases, your savings automatically increase as well. If you also increase the percentage of your income you're saving, you can gradually save even more. The average worker saves around 10% of their salary in their 401(k) -- which includes any employer contributions -- according to a report from Vanguard. If you save just an extra percentage point or two more of your salary each year, it can add up significantly over time.

Saving can be stressful, but it doesn't have to be as challenging as it seems. But adjusting your mindset and changing how you think about your financial goals, it's easier to get into a habit of saving more.