Estate planning. Getting your affairs in order. Securing your assets.

Chances are, these words bring to mind people in their golden years — baby boomers in their 60s and early 70s — not millennials. After all, they're the ones with estates and assets to manage, right?

But that mindset can be costly, say estate lawyers and financial experts. As morbid and depressing as it is to think about, unexpected injury or illness is just that — unexpected. So whether you're still in college, still have student loans to pay, are happily single, or are a new parent, it's never too early to prepare.

You'll be way ahead of your peers, too: Only 12 percent of millennials have a will, and just 36 percent of Generation X (ages 37 to 52) have one, according to a recent survey from Caring.org. A 2016 Gallup poll found similar results. It also discovered that Americans under the age of 30 actually became less likely in recent years to have a will — 14 percent in 2016 compared to 24 percent in 2005.

Fortunately, getting a head start is not terribly complicated, although it does require making some tough decisions, as well as an investment of several hundred dollars or more, depending on how complex your plan is.

Here are the top five things for your to-do list — think of it as a version of an emergency "To-Go Bag" for you and your loved ones.

1. Choose a health-care proxy

The health-care proxy establishes who you trust to make medical decisions for you if you can't make them for yourself. It's a pretty simple document that requires only two witnesses and their contact information to be valid.

Accidents happen, and if you're unconscious or otherwise incapacitated, you'll want someone who knows you — not a stranger — to act according to your wishes and in your best interests. This could be a parent, sibling, spouse/significant other, close friend, or even lawyer — whoever you trust with your life and, ideally, who can think clearly in stressful situations.

Even college students should choose a health-care proxy, advises Joanne Seminara, a partner at Grimaldi & Yeung LLP law firm in New York who specializes in estate and special needs planning, and co-author of 5@55: The Five Essential Legal Documents You Need By Age 55. Why? Because if you're a legal adult, not even your parents access your medical records or make health-care decisions for you.

"Let's say you're at college or away in a different state, and have a traffic accident; your mother can call till she's blue in the face, but the adult child has privacy rights," Seminara explains. "I went through that with my son, too."

In addition, while designating your health-care proxy should be enough, you can also choose to sign a HIPAA Release form that waives your right to privacy, in favor of your proxy agent. It's basically a backup form that confirms your decision.

If you don't choose a proxy, the state will do so for you, and sometimes family members end up fighting over what type of health-care treatments you can receive. Prevent that by having your say now.

2. Write a living will

In a worst-case scenario, your health-care proxy would have to make end-of-life care decisions for you — having a living will in place will make that easier for them and give you peace of mind. Basically, it outlines whether and "what extraordinary measures might be taken to keep you alive," says Seminara.

For example, if you don't want to be resuscitated, you could sign a DNR — a Do Not Resuscitate order. Or if you want to have your organs donated, that is also something you should put in writing.

A living will is something that needs to be prepared by an estate lawyer, who, while they're at it, could also help you set up your regular will.

3. Write a regular will

According to the Caring.com survey, 29 percent of those without a will said they "don't have enough assets to leave anyone."

That common misconception shouldn't stop you, though, as a last will and testament is more than just about the money.

Yes, a will serves as "instructions" for who gets what of your bank accounts and assets, says Seminara, but "even if it's not a lot, how are your next of kin going to know where to begin to look for assets and what's needed in case of a court procedure?"

So name a beneficiary and an alternate beneficiary for each of your accounts — the people who would get all or part of your money, investments, and any property (think homes, apartments, and cars) you own.

If you have joint accounts with a parent or spouse, or if you've already named a beneficiary, that person automatically gets access. If no one is named, your family members, significant other, and ex-spouses might end up fighting in court over who gets what.

"It's important to have someone who knows what your affairs are. If you use an attorney, they should also have a list of that info — bank accounts, any property or investments, etc. — in a file."

For millennials, assets also increasingly include social media accounts, photographs, and even things like credit card mileage points. Whoever you choose as executor of these accounts would be able to access or close them as necessary.

For young parents, a will is especially critical. "This way they can name a guardian, as well as an alternate guardian, who shares your values to raise that child," Seminara explains. "So consider who gets the child, and who is the trustee for funds to support the child if you have no spouse. Typically, you put that money in trust and choose someone with business acumen or investment interest to manage it."

4. Choose a power of attorney

Estate plans should also include someone to wield power of attorney — the person who acts as your legal representative and can pay rent and gas bills, make insurance and student loan payments, renew your lease, withdraw money, transfer assets, and sign checks on your behalf. They can even apply for Medicaid or disability benefits for you, and consult a lawyer in your stead.

According to Seminara, power of attorney documents usually run around 13 pages long, must be notarized, and should be handled by a licensed estate planning lawyer.

5. Talk with your loved ones

The final step is to discuss your plans with the people who you'd like to take on these responsibilities. It's important to make sure they're okay with being your health-care proxy, or your power of attorney, or your child's guardian. These conversations can also help you determine, based on their reaction, whether they are indeed the person to handle your affairs.