Planning for Retirement? Let These NFL Players Be Your Teachers. Our nation faces a retirement crisis, but six football players may have figured out the right path that we should all be taking.

Our nation faces what has been labeled a "retirement crisis," given the fact that the majority of older Americans --including many entrepreneurs -- aren't on track to meet retirement savings goals.

Related: How to Pay Zero Taxes Legally in Retirement

In fact, a quarter of Americans are planning for Social Security to be their primary income source during retirement, according to a Personal Capital survey. However, the Social Security Trustees annual report this year predicted that Social Security was likely to be depleted by 2034.

Related: 7 Wealth-Killing Risks That Threaten Your Retirement

Alarmingly, people aren't responding to that news: The Personal Capital survey found that 34 percent of Gen-Xers, 39 percent of millennials and 32 percent of Baby Boomers had not saved any money for retirement. Yet, about half of those surveyed also stated that they planned to retire earlier than the year that would get them the maximum amount of Social Security benefits -- assuming they'd get any benefits at all.

Michelle Brownstein, a certified financial planner and VP of private client services at Personal Capital, highlighted the importance of effective planning for the future: "The Social Security blind spot can be a major issue as younger generations approach retirement age," Brownstein wrote on the company's blog. "But it is possible to succeed with your retirement goals without depending solely on Social Security. Starting now is crucial for this, and the longer you wait to take action, the more difficult the process will become."

So, it's clear that many Americans are not on track for a secure retirement. But, what should any of us be doing about it?

The answer isn't just to earn more. Making a significant amount of money doesn't guarantee you'll be financially set for life. Just look at the National Football League: It pays an average salary of $2.1 million per player; yet 15 percent of NFL players declare bankruptcy.

Still, I can name at least six NFL players who seem to have figured out the path to long-term solvency. They recently shared with CNBC and other news outlets how they were able to save by stashing cash in investments and retirement savings. Here's what you can learn from their strategies to inform your own retirement planning choices and actions.

1. Saving always means living below your means.

Learn a valuable lesson from Detroit Lions wide receiver Ryan Broyles. Despite a $3.6 million rookie contract, he spent only $60,000 a year during his playing years, and invested or saved the rest, according to the CNBC report. Baltimore Ravens player John Urschel lived on less than $25,000 a year despite making $600,000, according to TheCheatSheet.com. That kind of discipline will ensure these players are in great shape for retirement.

Antonio Cromartie is a great example of a player who learned this the hard way. He signed a five-year deal with the San Diego Chargers and promptly blew through $5 million in two years. After teammates and his own agent asked him to slow down and see an accountant, Cromartie set up a system to automatically pay his bills and show him where his money was going each month; that way, he could stick to a budget and save as much as possible during his playing years.

It's not just these few football players who get this point: Many of today's wealthiest people know that spending significantly less than you take in is the path to acquiring wealth.

2. Find a side hustle that lets you save most of your salary.

A least one NFL player, Rob Gronkowski of the New England Patriots, managed to save all of his salary and live off just the money from his endorsement deals, according to Time.com. The lesson for today's entrepreneurs who pursue their businesses as a side gig to a salaried job is that, in the best cases, you can bank all of your salary from one gig while fully supporting your life with income from the other.

Of course, the goal for many of us is to grow a side business large enough to replace a regular job completely. But until you reach that point, don't forget that your side income shouldn't be seen as just "extra" money -- it's a critical part of your retirement strategy.

3. Don't just sock it away -- invest it well.

As a group, the Detroit Lions have been role models for wise retirement planning, it turns out: Glover Quin, who plans the position of safety, has built a safety net for retirement by investing. He has been saving 70 percent of his $6.5 million annual salary since starting with the team, as well as investing it, according to the CNBC report.

Quin ultimately hopes to double his money through wise investment choices. Doubling your money may sound ambitious to many, but even a modest 7 percent return on investments will help you achieve that in about a decade.

Marshawn Lynch is another financially savvy investor. The former Seattle Seahawks running back made nearly $50 million during his nine seasons in the NFL, Business Insider reported, and saved it all for retirement, knowing his career would be short-lived in the grand scheme of things.

Between that foundation and the $5 million he makes annually in endorsements, Lynch found that his thrifty ways enabled him to retire at the early date he'd planned for. Best of all, he paid the investment mindset forward: He helped fellow teammates build their own 401(k) plans, according to FanSided.com.

But you don't have to be a pro athlete with a giant salary to take advantage of the principles these six players are teaching, by example.

Related: What Is $1 Million Really Worth in Retirement?

Staying disciplined with spending, investing your savings and growing your side business can benefit you or any American with the vision and gumption to view their working lives through the perspective of the long haul. In the end, those who take this path will very likely be able to enjoy a secure and comfortable retirement.