Source: Social Security Administration.

Your retirement will likely require the largest investment effort you'll ever make. Your money, combined with Social Security and any pension you may have earned, will need to cover your costs of living for the rest of your life. If your health remains strong, a 30- or 40-year retirement is quite possible, which could mean you'd be retired nearly as long as you worked.

As daunting as it may seem to prepare for a retirement that could last decades, the good news is that so long as you're still drawing a paycheck, you can do something to help your cause. The sooner you get started, the easier it is to build a sufficient nest egg to last you throughout your retirement. But even if you didn't start saving with your first paycheck, you can improve your retirement outlook.

Retirement planning -- by the decade
If you're in your 20s, then this is your miracle decade for retirement funding. The money you put away now can potentially compound for nearly 50 years before you need it to cover your costs. If you sock away $500 each month during your 20s and earn a reasonable return of 8% per year, your retirement account could swell to nearly $2 million by the time you turn 70.

Time is your friend in your 20s, but the fact that you're just starting out in life makes saving a bit tougher. Your salary is likely lower now than it will be once you have experience and a solid reputation, and you're likely facing the costs of starting up your independent life. Still, because compounding can do so much for you at this stage of the game, it is certainly in your best interest to start investing for your retirement immediately. Live like a broke college student if you have to, but let this decade work for you.

If you're in your 30s, then this is probably the most important decade for your retirement funding goals. By this point, you've likely gotten past the entry-level salary phase of your career and established your household. Additionally, your children probably aren't yet of college age, while your own parents are likely still young and healthy enough to live independently.

In your 30s, you're likely to have a great balance between relatively low costs and high compensation, so you can save aggressively while time is still working in your favor through compounding. Mind you, in your 30s, time is not quite the miracle worker that it was in your 20s. You'd have to sock away around $1,000 per month during your 30s to wind up with around $1.8 million by the time you turn 70, assuming annual returns of 8%.

If you're in your 40s, then you can still find your way to a comfortable retirement by significantly funding your qualified retirement plans such as your 401(k) and your IRA. Be forewarned, though, that with much less time for your assets to grow, you'll need to save much more aggressively in order to retire in comfort. Still, if you start on your 40th birthday and invest $1,000 per month consistently until your 70th birthday, you could wind up with nearly $1.5 million in your account if you earn 8% per year.

Note, however, that your 40s may also be an expensive decade for you financially. In your 40s, you're more likely to become part of the "sandwich generation," supporting both your young-adult children and your aging parents. Additionally, any children you had in your 20s and early 30s may be heading to college. As tough as it may seem to get started in your 40s, retirement saving is a big priority, because waiting longer makes it substantially more difficult.

If you're in your 50s, then you're eligible for catch-up contributions to your 401(k) and IRA on top of the regular contribution limits available to younger participants. Because your 50s may well be your peak earning years, you may be able to take advantage of those higher limits. You'll need to invest $2,500 per month from your 50th birthday until your 70th birthday, compounded at 8%, in order to wind up with around $1.5 million by age 70. 

That $2,500 per month works out to $30,000 per year. The 401(k) limit with catch-up contributions will be $24,000 in 2015, and the IRA limit with catch-up contributions will be $6,500 in 2015. Together, that works out to $30,500 -- making it possible for you to invest that much in your tax-deferred plans. While the tax benefits will help, that's still a big commitment, particularly if you haven't been saving previously.

If you're in your 60s and haven't started saving for retirement, then much of what you have available to you from a planning perspective is based on the trade-offs of time versus money. For instance, you can start taking Social Security anytime between age 62 and 70, with your payment increasing the later within that window you get started. If you're able to keep working, each year's delay in taking your Social Security benefit within that window adds around 8% to your Social Security payment.

In addition, your 60s are a great time to figure out ways to cut down your costs of living. By this point, your house may well be paid for, and your kids are likely to be grown and independent as well. With those costs largely in your rear-view mirror, and your own health likely still good enough to keep you living independently, you ought to be able to keep your costs down and free up some substantial cash to invest.

If you're in your 70s or better, then at minimum, you should also be receiving Social Security on top of your paycheck. There's no benefit to waiting past your 70th birthday to start your Social Security payment. If you were covering your costs prior to taking that Social Security check, then you ought to be able to also collect Social Security and use that extra to help pad your nest egg for the day you do decide to stop working.

No matter what your current age...
The sooner you get started planning for your retirement, the easier it is for you to save up the money you'll need to put the "gold" in your golden years. Your first paycheck may be just a memory at this point, but the time between now your final paycheck can make a huge difference in your financial future. So get started now and begin looking forward to financial freedom.