Raise your hand if you've ever wasted money on something. All of us have done it, whether it's on that cool gadget you never actually used, the vacation that was no fun at all, or the pair of shoes that sat unworn in your closet for years.

Money management is tough even for those who are diligent about keeping their spending in check. That might explain why only 28% of Americans are considered financially healthy, according to a survey from the Financial Health Network. The report also noted that nearly half of Americans are spending as much (or more) than they earn, and more than a third said they can't pay their bills on time.

You may be pinching pennies where you can to save more money, but there are also non-obvious ways you could be wasting money without even realizing it. These things may not seem harmful at first glance, but if left unchecked over several decades, they can eat away at your savings and make it harder to financially prepare for the future.

Man letting coins slip through his fingers

Image source: Getty Images

1. Paying high 401(k) fees

If you're already contributing a little bit of each paycheck to your 401(k), well done -- you're already ahead of the two-thirds of Americans who aren't saving anything in their 401(k) accounts, according to Bloomberg.

However, your money may not be working as hard as it should if you're paying sky-high 401(k) fees. Fees are a necessary evil with 401(k)s, but 37% of Americans mistakenly believe they're not paying any fees at all, according to a survey from TD Ameritrade. Furthermore, of those who are aware they're paying fees, only about a quarter of them know just how much they're paying.

The average 401(k) holder pays fees of around 1% of assets managed, the Center for American Progress found. That means if you have $100,000 in your 401(k), you're paying $1,000 per year in fees. Over time, that money adds up. The Center for American Progress also noted that the typical worker paying 1% in 401(k) fees can expect to pay around $138,000 in fees over a lifetime, assuming he or she started saving at age 25. By increasing the annual fee slightly to 1.3%, though, that number jumps to $166,000.

If you're not sure what you're paying in 401(k) fees, check your plan's prospectus (which is essentially a legal document outlining all the nitty gritty details about the plan) or talk to your plan administrator. If you're paying higher-than-average fees, consider your options. You may not be able to change your 401(k), but you could potentially open an IRA with lower fees. In that case, though, it's still a good idea to contribute enough to your 401(k) to earn the full employer matching contribution, if your company offers it -- after all, free money is free money. 

2. Not paying down high-interest debt first

If you have multiple types of debt, it may seem logical to start paying off the debt with the largest outstanding balance. But really, it may be more financially wise to knock out the most expensive debts first.

Not all debt is created equal, and high-interest debt is the worst offender. In some cases, you may be paying upwards of 20% in interest, and the longer it takes to pay off that debt, the more money you're wasting in interest payments.

For example, say you're carrying $7,000 in credit card debt paying 16% APR, and you're making payments of $100 per month. At that rate, it will take more than 11 years to pay it off completely, and in the process, you'll have spent around $7,300 in interest alone. However, if you had increased your monthly payment to $150, you'd be able to pay off that debt in around 5 1/2 years, paying approximately $3,500 in total interest.

In short, the faster you can pay off high-interest debt, the more you'll save -- and those savings can then be put toward other goals like retirement.

3. Keeping money in a savings account rather than investing it

After the Great Recession, many Americans were understandably cautious about investing their money in the stock market. From 2009 to 2017, only around half of Americans said they had invested in stocks, a Gallup poll found. While it may seem risky to put your money in the stock market, it's even riskier to stick it in a savings account.

The stock market has its ups and downs, without a doubt. You'll see good years and you'll also see bad years, but over time, the market experiences an upward trend. The S&P 500, for example, has seen an average historical return of around 10% over the last 50 years. So while you may experience the pain of a recession or two, the markets (and your savings) have inevitably bounced back if given enough time.

Savings accounts, on the other hand, have much lower rates of return -- even the highest-yielding savings accounts offer interest rates of just 1% to 2.5% right now. That's great if you're stashing your money for short-term financial goals, but for the long-term, those rates can't even keep up with inflation. In other words, your money may actually be losing value if you keep it in a savings account long-term.

The stock market isn't as risky as it seems, especially if you invest in index funds and mutual funds -- where your money is divided up between dozens or even hundreds of different stocks, bonds, and other assets to limit risk. You can lose money over the short run, but when left untouched for a few decades, your money will likely grow exponentially faster than it would in a savings account.

Saving money is hard, but it's even harder if you're unknowingly spending more than necessary on fees and interest and losing out on potential savings. If you're struggling to save now, consider where all your money is going. It could end up saving you thousands of dollars you didn't know you had.