While the prospect of living longer excites most Americans, the necessity of needing more retirement savings is causing more and more concern for younger generations.

Americans are expected to live on average 30 years longer than a century ago — according to research from the Stanford Center on Longevity — and while 93% have a favorable view if living those extra years, 70% feel financially unprepared to live to 100 or more. According to the study — by insurance company Allianz Life — the financial concern is greater for the younger generations. Nearly eight out of ten — 79% — of Gen-Xers said they feel financially unprepared for living longer, while 74% of Millennials had the same concerns.

"Americans, in general, should feel financially unprepared for longer lifespans," said Kevin Gallegos, a vice president for FreedomFinancial Network. "This is because most people do not have enough saved, period. They don't have enough in just an emergency fund, let alone in retirement funds."

Gallegos said there are variety of reasons people feel unprepared, including the financial crunch many feel since they are helping their children get established or caring for aging parents. Also, many are just understanding the cost of health issues that come up later in life, and some — especially Millennials - are realizing that Social Security may not be there for them, he adds.

While there is no perfect way to know exactly what one will need as he gets older, Gallegos said there are a handful of things one can do to at least try to prepare.

"Estimate how much you'll need," he said. "It's hard for a Millennial to do this, but it's possible to make an estimate, and continue to revise that throughout life."

He adds to invest the maximum — from the beginning — in a company 401(k) plan if it is available, as well as an Individual Retirement Account (IRA), and pay off debt, particularly any credit card debt.

"Paying off a credit card balance with a 15% annual interest rate is equivalent to earning a 15% return on an investment - far better than any savings fund," Gallegos said.

While having a plan is important, Rick Dwyer, CEO of Wealth Financial Group First Coast in Jacksonville, Fla., said don't forget to revise the plan as life goes along.

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"Life has a way of changing in ways we never anticipated," Dwyer said. "Some of these changes will be positive and others will be negative. By adjusting your plan throughout your working years you will increase the likely hood that you will reach a retirement that you will be comfortable with."

Dwyer also suggest work with a financial professional who has a focus in retirement planning.

"Working with a professional will help to ensure that you are utilizing realistic expectations in your planning and that you are considering items such as inflation and taxes," he added.

David Adams, founder of David Adams Wealth Group in Nashville, said once upon a time people used to plan for an early retirement, but today such a thing is pretty much just a dream.

"Back in 1991, half of all American workers planned to retire before they reached the age of 65," he said. "Today, that number has plunged to just 23%."

He recommends using a three-bucket savings system to help plan — with a bucket for emergency funds, mid-term goals and retirement.

"Once you've got your emergency fund set up … you can start putting 15 to 20% of your gross household income toward retirement," Adams said. "In addition to that, look into a Roth or traditional IRA."

While there is no magic bullet to assure a perfect retirement, planning can alleviate some concern, and lets one know they are on track and when they need to adjust course, Dwyer added.

"Having a plan doesn't guarantee a successful retirement, but it does give you information that can be very beneficial while preparing and living in retirement," Dwyer said. "Planning at any age is the best strategy a person can implement to navigate the changes that will happen as you approach and then enter into retirement."