There are various challenges to maintaining financial health in one’s later years, but one of the biggest is this: understanding the sheer scope of that challenge. In too many cases we move along in our pre-retirement years, only vaguely aware of the potential trouble ahead; we are either unwilling or unable to confront the stark reality.

So here it is: We’re going to need a lot of money in our Golden Years, and most of us don’t have it. Respondents to a Schwab poll, all of whom held 401(k)s, estimated they would need $1.7 million.

Yes, $1.7 million.

Investopedia noted that most experts believe you will need 80 percent of your yearly income following retirement — i.e., if you make $100,000, you will need $80,000 — and cited the Four-Percent Rule for savings. In other words, you divide your desired nest egg by .04. To continue bringing home the $80,000 cited by Investopedia, you would need $2 million for the duration of your retirement.

Let’s toy with some more realistic numbers. The average U.S. salary is just over $56,000. The average retirement age is 62, and the average life expectancy is about 79. Eighty percent of $56,000 is about $45,000. Multiply that number by 17 — as in, the number of years the average person can expect to spend in retirement — and you get $761,600.

That, of course, is simplistic, considering the ever-rising costs of healthcare and housing, just to name two. Reality, then, lies somewhere between $760,000 and $1.7 million. Either way, it’s a big number, and according to the Stanford Center on Longevity, most Baby Boomers can’t approach it; three in 10 don’t have any money set aside for retirement, and of those who do, their average savings are under $300,000.

A website called listed 10 money-saving tips for seniors — everything from hiring a certified financial planner to growing one’s own veggies, from buying generic meds to carpooling — but the best advice might be this: Have a plan. Take a holistic view of your life. Map things out. Discuss things with your loved ones, particularly your children.

That same site referenced An Action Plan for Successful Aging, which underscored the difficult financial questions seniors must tackle, and how it is best to make it a group project. Moreover, those matters impact decisions about housing, health and end-of-life choices, all of which are among those things also mentioned in the report.

There is, in other words, much to consider. But the biggest of all is the sheer amount of money that will be needed. For that reason it is of enormous importance to have a plan, and to develop it well before retirement.