A 26-year-old set to retire at age 37 shares the book that shaped his mindset about money

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You don't need an inheritance or a windfall to retire early — you don't even need a six-figure income.

All it takes is smart saving and investing habits, says one millennial who is well on his way to retiring at the age of 37.

"The Money Wizard," who goes by the pen name Sean and asks to remain anonymous, saves more than 60 percent of his $70,000 salary. His savings rate puts him on track to accumulate $750,000 in the next 11 years, which he says will be enough to let him comfortably retire.

The 26-year-old committed to fast-tracking his retirement after reading Jacob Lund Fisker's "Early Retirement Extreme" at age 22.

"The book changed my whole outlook on a working career," he tells CNBC.

"I had always assumed, like most people, that I needed several millions of dollars to retire. Yet here the author was proving retirement was possible on far less than I ever imagined. It's not one size fits all for everybody — it depends on how much money you spend and what your expenses are."

Sean then started reading about people such as Mr. Money Mustache, who averaged a $67,000 annual salary for 10 years before announcing his retirement at age 30, and Jeremy Jacobson and Winnie Tseng, whose combined annual salary of $135,000 allowed them to retire in their 30s with a multimillion-dollar net worth.

"These people using their savings to retire early just proved to me that big spending is really nothing more than a trade-off between material goods and years of freedom," says Sean.

Really think through everything you spend money on, he encourages, and question whether or not your purchases are actually bringing you happiness: "Is a car that costs $30,000 really going to make you that much happier than a car that costs $20,000? Or would you be happier saving that money so you can one day be financially free?"