Retirement should be one of the most joyous times in your life, and successfully preparing for it is a huge accomplishment. However, there's a lot more to retirement preparation than simply transferring a portion of your paycheck to your 401(k) on a regular basis.

Retirement is a complex topic, and if you're not 100% confident that you're preparing the best you can, you're not alone. In fact, 60% of Americans are unsure how much they'll need to save for retirement, according to a survey from TD Ameritrade, and 51% don't think they'll have enough to adequately cover their needs.

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The scary truth is that forgetting even one part of the retirement equation can quickly derail your plans. Even if you think you have a solid plan in place with enough savings to last you through your golden years, there are a few things that can ruin your retirement.

1. Healthcare costs

Healthcare is one of the biggest expenses you'll face in retirement. The average 65-year-old retiree can expect to spend roughly $5,000 per year on out-of-pocket healthcare expenses in retirement, according to a 2018 study from Fidelity Investments. That also doesn't include long-term care costs, which can amount to thousands of dollars per month (the average cost for a semiprivate room in a nursing home is nearly $7,500 per month).

If you're expecting most of these costs to be covered by Medicare, you may be in for a rude awakening. Medicare can help with a lot of your healthcare expenses once you become eligible to enroll at age 65, but it doesn't cover everything. You're still responsible for deductibles, premiums, copays, and coinsurance, and Medicare also typically doesn't cover routine care (like most dental care and eye exams) or long-term care.

So, needless to say, if you're not planning for these costs, you could be in for quite the surprise once you retire and realize you can't afford to pay for healthcare. By doing your research ahead of time, though, and choosing the right Medicare plan for your unique situation, you can plan for most of these expenses before they break the bank.

2. Not having a solid retirement plan and budget

It's one thing to know how much you need to have saved by the time you retire, but it's arguably even more important to know how much of those savings you can withdraw each year so that your retirement fund lasts as long as possible. Because even if you have $1 million when you retire, if you're withdrawing $100,000 per year, your savings will only last about 10 years.

To figure out how much you can realistically withdraw, a good rule of thumb is the 4% rule, which states that you can withdraw 4% of your total savings during the first year of retirement, then adjust that number each year following to account for inflation. So if you have $500,000 saved by the time you retire, you can withdraw $20,000 the first year of retirement. (Keep in mind, too, that you'll also likely have Social Security benefits to cushion your personal savings.)

To determine whether that will be enough, you'll need to come up with a retirement budget. You may not necessarily be spending the same amount in retirement as you are now, so it's important to consider how your financial needs will change once you leave the workforce. For example, you may be spending more on healthcare, but you could be spending less on gas and dining out when you no longer commute or buy lunch at the office every day.

Before you even think about retiring, you'll need to have an estimate in mind for how much you'll be spending each month and year. Once you have a budget, you'll be able to determine whether you have enough saved to cover all your expenses, or whether you'll need to cut back during retirement (or work a few more years to continue saving).

3. Investing too conservatively

Sometimes choosing where to invest your money for retirement can seem a little counterintuitive. You may think that it's best to invest conservatively so that you lessen your risk of your investments losing value before you retire. However, invest too conservatively, and there's no way you'll be able to save enough to retire comfortably.

For example, if you're investing in a money market fund or CD and earning a 2% annual rate of return, yet you also see an annual inflation rate of 3%, your investments will actually be worth less in the future than they are now. While stocks are inherently riskier, they typically see annual returns of 8% to 10% over time -- so even if your investments experience occasional dips, you'll likely still see greater rewards overall by the time you're ready to retire.

It's also important to remember that you won't stop earning returns on your investments once you retire. So while it may be tempting to transfer all your money into more conservative investments as soon as you retire, that will only stifle your savings and make it harder to ensure your money lasts the rest of your life.

There are dozens of factors to consider when planning for retirement. It's a lot of work to ensure you're covering all your bases, but the results will be worth it when you're able to enjoy the retirement of your dreams without worrying about running out of money.

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