About 70% of Americans don't have a will. Yet every adult, whether they are young or old, wealthy or not, should have one. Why? It's quite simple. Without a will, a legal document that tells the world how you want your assets distributed after your death, there is no guarantee that your wishes will be followed when you die.

Need more specific reasons? Here are five.

1. You just never know.

Generally, we assume we will die in our old age, preferably while napping, many years down the road. Therefore, we think we have a lot of time before we need to think about preparing a last will. But, the simple truth is, we don't know when we will die.

If a person dies unexpectedly and never prepares a last will, most states take it upon themselves to figure out how the assets should be distributed. Surviving spouses and children usually get top priority but often a state court judge is the final decision maker on the future of your property.

State laws differ widely. In some cases, if you die without a last will and have no surviving relatives, your entire estate goes to the coffers of your state government.

2. Your children may end up in the care of someone you didn't even like.

Let's be clear. If you have children, you absolutely need to have a will drawn up as soon as possible. Should you die while they are still minors, your children's guardianship is far too important to leave to chance.

A will enables you to select a guardian and a trustee to manage their affairs. Without a will, a court will appoint a guardian and/or trustee who may not be your first choice. Remember, if you decide to select someone other than the child living parent as a first choice, you may want to explain the reasons just in case the living parent challenges the will.

3. Your baby silverware (and/or dog) may end up with cousin Maude who you haven't spoken to since, well, you could speak

You may not think you have enough to warrant writing a will, but if you own anything at all, you should have a will. Without writing down who should go to whom, it will be left to the state to decide even if your preferences had been made clear verbally to your family before your death. The only way to be sure that your wishes are followed is to write a will.

Remember that state law considers pets personal property, so do think about your furry friends when writing out a will. You may want to name a caretaker and even leave money to your pet's guardian for the animal's future care.

4. That echoing cackle you hear? That's Uncle Sam!

They say that the only certain things in life are death and taxes, and make no mistake, the two go hand in hand. Depending on the size of your estate, you can be hit hard with both taxes and probate costs, so it's best to plan ahead so that your loved ones end up with the bulk of what you've worked so hard for.

Remember that tax laws are constantly changing on both the state and federal levels, so stay abreast of any changes that may affect your estate plan. An attorney who specializes in wills and estate planning is your best bet here, but you can keep yourself informed as well.

5. Your favorite charity will miss your donations.

Charities, schools, churches, and other organizations that have become a part of your life may be forgotten if you don't provide for them in your last will. Again, your family members may know how important your charitable giving was to you, but without explicit written instructions, they are not obligated to provide any further donations.

So now that you have decided to write a will, what do you do?

Contrary to popular belief, writing a will doesn't have to be expensive, and it may not even require an attorney. LegalZoom.com can help you prepare and even update your will from the privacy of your own home.

And remember, you can cancel or rewrite your last will at any time before your death. What you decide now doesn't have to be the truth forever. In fact, you may want to revise your will after any major life events like marriage, divorce, moving to a new state, the birth of a new child, or the death of loved one.

Just be sure that after you've written and signed your will, make sure it's safe and accessible. You might even want to let another person, like the executor, know where to find it. Good locations for your will include a fireproof safe or a safety deposit box—just make sure you know your bank's policy about accessing the box after you die.

And now, knowing that your wishes will be followed and your loved ones will be cared for after your death, you will be able to rest in peace even before you meet your demise.