When it comes to planning for retirement, most of us are just trying to do our best — juggling advice from financial gurus, our instincts, and maybe a sprinkle of wishful thinking.

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According to the U.S. Department of Labor, only about half of Americans have calculated how much they need to save for retirement. But even with the best intentions, there’s one common mistake that trips up a lot of Americans. And the worst part? It’s often hiding in plain sight.

GOBankingRates spoke with Andrew Lokenauth, money expert and owner of Be Fluent In Finance, and Chris Heerlein, CEO of REAP Financial, to discuss the top mistake Americans make when planning for retirement.

Here’s what they had to say.

Waiting Too Long To Start Saving

In his years as a financial advisor, Lokenauth has seen one massive mistake come up over and over –waiting too long to start saving.

And he’s not just talking about waiting until your 40s or 50s.

“I’ve watched countless people in their 20s and 30s push off retirement planning, thinking they’ve got all the time in the world. Trust me, they don’t.”

Here’s what drives him crazy: People constantly tell him, “I’ll start saving when I make more money” or “I’ll get to it after I pay off my student loans.”

But he explained that mindset costs them hundreds of thousands in lost compound interest.

“I had a client who waited until 45 to start saving — he needed to put away 3x as much monthly compared to if he’d started at 25,” said Lokenauth.

So here’s what he tells his clients: Start now, even if it’s small.

Put away $50-$100 per month into your company’s 401(k), at a minimum, enough to get any employer match (that’s free money). At the same time, open a Roth IRA and set up automatic monthly transfers.

“Even $25-$50 helps build the habit. I’ve seen this strategy work countless times.”

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Failing To Create a Reliable Income

According to Heerlein, the biggest mistake is thinking retirement is all about hitting a savings number, rather than creating a reliable income strategy.

He noted that too many people fixate on reaching $1 million or some other target without asking what that money needs to do for them.

“I’ve worked with clients who had large balances but no plan for how to take income efficiently, how to manage taxes, or how to handle health care costs over 20 or 30 years,” said Heerlein.