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38-year-old retired millionaire: One simple habit leads to wealth

Holly Whittlef. Chris Reining spends hours reading each week. Here are his top picks.

Chris Reining's career started out according to plan. "I was working in IT and it was my dream job for a while," the now 38-year-old tells CNBC.

He bought a condo and a BMW and shopped at Whole Foods every week: "I was living a pretty good lifestyle. But in my late 20s, I started becoming a little disillusioned with the whole 9-to-5 grind. It was so repetitive."

Reining, who is based in Madison, Wisc., wanted something different, he says: "The freedom to do what I want to do, when I want to do it."

Reining set the goal of building a $1 million portfolio by age 35 and started working to save and invest, rather than working to spend. He got to the point where he was saving more than half his income, reached the $1 million mark at 35 and officially retired at 37.

He did it thanks to one simple habit: He automated his finances, he writes on his blog. That not only saved him money but saved him time and simplified his life.

Start by automating your retirement savings and have a portion of your paycheck sent directly to a tax-advantaged retirement account, such as a 401(k), Roth IRA or traditional IRA. Reining, along with most money experts, recommends investing at least 10 percent of your gross income .

If you're not comfortable making a 10 percent contribution, it's better to start small than not begin at all. "You can start with as little as $50," Reining writes. "The key is to start saving for retirement rather than doing nothing because you'll be better off than mostly everyone else."

Don't stop with your retirement savings. "Each month you can automatically pay your student loans, credit cards and rent," says Reining.

You can also automatically set aside money in an emergency fund or for bigger savings goals, such as a home, car and vacations. Simply link your accounts so that a specific amount of money goes from your checking account to your savings account, and set up the exact day you want to make transfers.

"I automated my money years ago, and the benefit is I don't have to make decisions about where my money should go, how much I should invest, what I can spend, do I have enough savings, and so on," says Reining.

In addition to simplifying your life and freeing up mental energy, you'll never forget a payment again or be tempted to skimp on savings. The best part is, you can start implementing this wealth-building habit today.

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