We're told time and time again to plan for retirement rather than wing it, and that's good advice. Planning for that milestone can help ensure that you're able to build adequate savings, determine what lifestyle you'll maintain as a senior, and figure out what you'll do with your newfound free time.

But as they say, the best-laid plans can often go awry, and a recent report by Allianz confirms that. Allianz found that a whopping 50% of Americans wind up retiring earlier than planned, with the majority doing so for reasons outside their control.

Older man typing on computer keyboard

IMAGE SOURCE: GETTY IMAGES.

For 34% of those forced into early retirement, that scenario came due to unanticipated job loss. For 25%, it came as a result of healthcare issues. Either way, the fact that half of older Americans wind up leaving the workforce sooner than expected is troubling, and should serve as a wakeup call for those in the process of planning for their golden years.

Don't wait to fund your nest egg

Many workers put retirement savings on the back-burner for years as they address more pressing financial goals -- buying a home, paying off debt, and putting children through college. These are all important things to focus on, but here's the problem: If you wait until your 50s or later to start building a retirement nest egg, and you're forced to leave the workforce earlier than expected, you'll risk falling seriously short on cash later in life.

Let's imagine your plan is to start focusing on retirement savings when you're 52 years old, with the goal of leaving your career behind at age 67. That gives you 15 years to save and invest aggressively. If you manage to sock away $1,200 a month during that period and your investments generate an average annual 7% return, which is a reasonable assumption for a stock-heavy portfolio, you'll end up with roughly $362,000 -- a decent-sized nest egg to tap during retirement. But what happens if you're forced to leave the workforce at age 62 instead? Suddenly, you're looking at just $199,000 -- not exactly a negligible amount of money, but nowhere close to $362,000.

The takeaway? It's fine to plan to save for retirement well into your 50s or 60s, but don't assume that option will be on the table, and don't neglect your nest egg earlier in life thinking you'll simply catch up later on. Instead, start saving from a younger age so that if you're forced to retire earlier than you'd like to, you won't risk falling dangerously short on funds throughout your senior years.

Another thing: When you're forced out of your career sooner than planned, you risk having to claim Social Security early to compensate, thereby reducing that income stream as well. If you start setting funds aside for your golden years during your 20s, 30s, or 40s, you'll put less pressure on your later working years -- and you'll have less to worry about if your retirement plans don't adhere to the schedule you initially map out.