The killer question, though, the one that everybody asks, the one that seems most difficult to answer, is the absolutely right question. It is "How much do I need to retire?"

Which brings us back to the singing nun and why her advice to "start at the very beginning" fails when it comes to retirement planning. Quite simply, to do retirement planning right, you need to start at the very end, and then work backwards.

It's something every financial planner will tell you and something every plan sponsor should advise their employees. There's a reason why they made that commercial with everyone walking around with numbers on their shoulders.

Now, any number of financial professionals have the wherewithal (or at least the appropriate application software) to determine a reasonable approximation that could answer the question "How much do I need to retire?" Despite the apparent "rocket science" nature of the question, this is probably the easiest step on the journey to retiring in comfort.

Actually, all the steps are pretty easy. It's the attitude that makes the whole process so difficult. But maybe I'm just saying that because I'm a left-brained kinda guy (that's the math side). Or maybe it's because I'm a right-brained kinda guy and in tune with my emotions enough to maintain the correct attitude. 

The specific attitude I'm talking about deals with "focus." In other words, once the 401(k) investor knows what the end goal is, that investor needs to focus on what it takes to achieve that goal. Without getting into the minutia of the academic research which supports this idea, 401(k) investors succeed more often when they concentrate on the factors they control (i.e., when to start deferring, how much to defer and when to retire).

From there it's all math, and a little bit of guesstimation when comes to projected investment returns. (For an example of how to do this, see "A How-To Guide: Investing Using the Total Return Method or the Assigned Asset Method")The basic idea, however, remains the same. You start at the end and work backwards to today.

Sure, there's bound to be a few different scenarios, but, again, these won't scare a financial professional. They can scare non-professionals, though, and their relevance just needs to be communicated to the 401(k) investor. Plan sponsors can best help their employees by insuring these scenarios are generally addressed in group education meetings. 

So, whether you're 60 going on 70, or you just want to retire with a few of your favorite things, the answer remains the same. First, know where you want to be. Then, reverse engineer the numbers to determine your strategy for getting there.