Deciding when to retire is a major life decision. According to a recent survey by consulting firm Willis Towers Watson, while the average U.S. worker expects to retire at 65, nearly a quarter of Americans anticipate working into their 70s. On the other hand, despite the financial challenges of retiring early, 11% of Americans are still aiming to leave the workforce between ages 62 and 64.

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So what's the right time for you to retire? First, here some key ages to know about:

  • 62 is the earliest age at which you can claim Social Security benefits, albeit at a reduced rate.
  • 65 is the age at which you're eligible for Medicare.
  • 66 is your full Social Security retirement age if you were born between 1943 and 1954, while 67 is your full Social Security retirement age if you were born in 1960 or later. Those born between 1955 and 1959 fall somewhere between 66 and 67.

With that mind, your retirement age will depend heavily on your personal circumstances. Here are three tips for finding your magic number.

1. Evaluate your health

Your health will mostly likely play a major role in your decision on when to retire, for better or worse. The Employee Benefit Research Institute found that 50% of workers retired earlier than planned last year, and of those, 60% cited health problems as the primary cause. If your health is on the decline, you may have no choice but to plan for an earlier retirement. On the other hand, if you're in good shape physically and feel you can continue working longer, doing so might help your finances significantly. Better yet, new data shows that working longer can also lead to a longer life.

Your health should also be a factor with regard to collecting to Social Security. While claiming early does result in a benefits reduction, if you don't expect to live well past your full retirement age, you might come out ahead by taking benefits as early as possible. Let's say your full monthly benefit is $1,200 and your full retirement age is 66. If you start collecting at 62, you'll reduce your benefits to $900 a month -- a 25% reduction. But if you only live until age 75, you'll wind up getting $140,400 in lifetime benefits. If you wait until 66 to collect Social Security, you'll get your full benefit amount each month, but you'll only end up with a lifetime total of $129,600.

2. Examine your savings

Do you have enough money saved for retirement? A shocking number of Americans don't. According to a recent survey by GoBankingRates, roughly 30% of Americans 55 and over have no retirement savings at all, while 26% have $50,000 or less. And if you think you can fall back on Social Security in the absence of savings, think again. Social Security was designed to supplement your income in retirement, not replace it. While you can generally count on Social Security to cover 40% of your pre-retirement income, most people need 70% to 80% of their pre-retirement income once they're no longer working. If you've saved enough money independently to make up the difference, you might be in a good position to retire sooner. Otherwise, you're probably better off working a few extra years as long as you're physically able to do so.

For 2016, anyone 50 or older can contribute up to $6,500 to an IRA and $24,000 to a 401(k). If your company offers a 401(k) match, you have even more reason to work longer, contribute to your employer's plan, and collect whatever free money comes your way.

3. Assess your career

Are you still enjoying what you do? Or do you dread going to work every day? Not only do studies show that working longer is good for your health, but there's evidence pointing to a decline in health once retirement kicks in. The Institute of Economic Affairs reports that retirement increases the probability of suffering from clinical depression by 40% and physical illnesses by 60%. If your job is satisfying and not overly stressful, working into your 70s could be the key to maintaining your mental and physical strength. On the flipside, if you're tired of the daily grind and can afford to retire sooner, you might choose to stop working when you reach your full Social Security retirement age or even earlier.

The tricky thing about choosing a retirement age is that there's no single right answer. What may be the ideal retirement age for you could be the wrong choice for someone else. So don't fixate on when the people around you decide to call it quits. Just focus on your own personal needs and goals, and with any luck, you'll wind up retiring at just the perfect time for you.