Millennial Money illustrates the benefits of investing in the stock market early in life and elaborates on the best strategies for doing so.

Despite being more worried about retirement savings than any previous generation, the majority of millennials are not utilizing the best tool for ensuring long-term wealth: the stock market.

Because this generation has lived through two stock market crashes, it's fair they would be wary of investing.

But according to Patrick O'Shaughnessy, investing in the stock market is an investment in the ever-growing world economy — it must pay back.

O'Shaughnessy is the CEO of his own quantitative money management firm.

In Millennial Money, O'Shaughnessy argues that youth trumps everything when it comes to investing, that long-term investments keep you safe from future risks, and that early small investments are the key to gaining large sums later.