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This isn't your daddy's retirement. And it's not for the faint of heart.

Do-it-yourself 401k's, IRAs and multiple-choice Medicare supplement plans have taken the place of the company pension plan, retiree health benefits and a gold watch.

And working into retirement -- in the form of a second (or third) career or part-time job -- is becoming the norm.

"It's a changing landscape," says Sara Rix, a senior strategic policy adviser with AARP.

But this evolution hasn't happened overnight, she says. "Some of the changes we're seeing began 20 to 25 years ago."

One major adjustment: People are working longer. In 1985, there were fewer than 1 in 5 65- to 69-year-olds in the workforce, Rix says. Today, it's almost 1 in 3 -- a 74 percent increase.

Some would-be retirees need the money, says Rix. Others enjoy their jobs and want to keep at it. And, for some, it can be a combination of the two.

Whether you're 25 or 75, you should know these seven things about retirement in the new millennium.

You're on your own

It's like one of those high school math brain-twisters: The amount you save times your compounded earnings, minus any investment losses and factoring for inflation, equals what standard of living at some (movable) future date?

Try solving for that "X."

But one thing is true: Save nothing now, and that's exactly how much you'll have when you retire.

"People have to be much more proactive," says Tony Webb, research economist with the Center for Retirement Research at Boston College.

A study by the Economic Policy Institute using the Federal Reserve's 2007-2010 Survey of Consumer Finances showed that half the people on the cusp of retirement (ages 56 to 61) had a retirement account balance of less than $91,000. At a typical drawdown rate of about 4 percent per year, that equals about $3,640 annually, or about $303 a month in retirement income, Webb says.

One big problem with everything financial is that you pick up skills as you move along -- and make plenty of mistakes along the way, says Webb.

And, unlike a lot of situations, the people retiring now can't look to past generations as a model because the game has changed, he adds.

Start planning early

It doesn't take a rocket scientist to calculate that saving for 50 years will yield more than saving for 20 years.

But what 20-year-old wants to forgo critical funds for a day that's so far off into the future?

That's why a recent Stanford University study has gotten so much attention, says Ruth Hayden, financial consultant and author of "Start Where You Are: Retirement Planning in a Changing World."

Researchers found out that when they showed young workers digitally aged photos of themselves at retirement age, workers were more willing to put money aside for their future selves.

"It changes their perception," Hayden says. And when it comes to planning for retirement, "that intellectual and emotional ownership is critical."

One big rule for the new retirement: Financial literacy needs to be a lifelong pursuit, says Rix.

Do it right, and money planning will be downright boring, Hayden says. "Plain-vanilla" strategies -- such as regular contributions, slow-and-steady growth and diversification -- are often most effective over the long haul, she says. It's also important to get advice from trusted, neutral advisers when you can afford it, she says.

Two of the biggest mistakes employees make are cashing out the 401k after a job change and leaving an employer's matching dollars on the table, says Hayden.

Money can be accessible

It used to be that when you put away money for retirement, you couldn't touch it until retirement -- except in some very limited circumstances.

That's not always true anymore.

With a Roth IRA, you can withdraw any money you contribute at any time without taxes or penalties, says Ed Slott, CPA and author of "The Retirement Savings Time Bomb ... and How to Defuse It."

The idea that retirement savings is locked up for a far-flung future date is a mental block for a lot of potential savers, says Slott. "That is one of the things that turned me off from (traditional) IRAs years ago," he says. "But now that's not the case with a Roth."

The nice thing about a Roth is those earnings won't be taxed during retirement. The trade-off with a Roth is that you don't get a tax deduction now when you make a contribution.

But continuous access to your money and the ability to grow it tax-free more than make up for forfeiting a one-time tax deduction, says Slott.

"When you make a $5,000 contribution to a Roth IRA, you have immediate access to that money," says Slott. "So if you need it, it's there."

You can contribute to an IRA

You contribute to a 401k through work. Or, you're a stay-at-home spouse with no income.

In either case, you can still probably use an IRA to save for your retirement, says Slott.

Workers already contributing to a 401k can most likely still make contributions to an IRA if they want, he says. "A lot of times they think if they're in a company plan, they're not allowed," he says. "But that's not true."

Earn above a set income, though, and you may not get the full tax deduction for your traditional IRA contributions, says Slott. But that income ceiling won't affect most wage-earners, he says. IRS Publication 590 provides details about IRAs.

With a Roth IRA, there is no tax deduction, "but there are some high-income limits for who can contribute," he says.

Not working outside the home? As long as your spouse is earning enough to cover the contribution, you can fund your own spousal IRA in your own name, he says.

With an IRA, you can bank up to $5,500 annually per person, if you're 49 or younger. Fifty or older? You can salt away up to $6,500 this year.

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