Imagine you're heading out to the pharmacy to pick up a prescription for a nagging cough. On the way, you stop by the ATM: You punch up your account for health expenses and take out $50 — no, make that $250. You'll pass the optician's on the way home, so you might as well stop in for the new pair of glasses you ordered.

It's no big deal. Of course a lot of your friends and colleagues complain about health expenses. Some don't get insurance because of the cost. Instead, they are annoyed by the quickly rising premiums, but not you — you're totally covered. And where they see increasing costs, you see opportunity.

Maybe you're an entrepreneur who is just starting out and you need to insure yourself. Maybe you're a small business owner and you need a good insurance plan to attract top-notch employees. Maybe you run a multi-million-dollar company and are looking to provide better insurance — and cut costs. Maybe you're a recent college graduate and aren't sure how you can afford health insurance.

In any of these scenarios, Health Savings Accounts just might be the perfect solution for you. And you don't have to be an accountant or a health care genius to figure them out. Anyone can do it — even those prodigals who are taking the risk of running without insurance. It's worth your time to investigate because this whole new way of paying for medical expenses has begun to transform American health care.

Health Savings Accounts are just two years old, but they're already a proven success. Over 3 million have been established so far, and more and more savvy folks are coming on board every month.

A Health Savings Account? What's that? Millions of otherwise intelligent people still don't have a clue. And sadly, that includes a lot of entrepreneurs, small business owners, and young people just starting out on their careers — those who stand to benefit most from HSAs.

They're really not so complicated. An HSA makes health coverage more like, well, insurance. After all, the reason you buy car insurance is to protect yourself in the event of a catastrophe. Routine things like maintenance and minor repairs you take care of yourself. You don't "insure yourself" against a flat tire or a new turn signal bulb.

Say you have a car accident. For your car, you pay your policy's deductible, and your car insurance company takes care of the rest. If you're an HSA holder and you're injured in that accident, you pay your health policy's deductible, and your health insurance company takes care of the rest. What's more, you're allowed to pay your medical care deductible out of tax-free money you've socked away in your own interest-bearing Health Savings Account.

That's the peace of mind HSAs provide. You set up your health-only, tax-free bank account paired with what's called a "high-deductible" health insurance plan. That plan is a low-cost policy — cheaper than traditional insurance — that protects you from really big-hit medical bills.

However, you pay your routine costs: doctor visits, prescription medicines, eyeglasses. The insurance plan kicks in after you've paid the first $1,050 to $2,700 in expenses, depending on your plan. Many plans offer at least one free "wellness" visit — a physical and/or OB/GYN appointment — a year, as well.

Part of what makes HSAs so revolutionary is how you pay for those routine expenses. The Health Savings Account is a tax-free bank account — sort of like a 401(k) retirement account. You don't pay taxes on the money you contribute to it. And you're not taxed on it if you use the money for qualified health expenses. That's no small advantage — no tax means you start out saving around 30 cents on every dollar you deposit into the account.

And if you don't use all your money during the year it is no problem. Your savings roll over into subsequent years. In fact, you earn interest on money that stays in your account. So if you're relatively healthy, you can build up a pretty nice nest egg for when you're not. If you're an employer, you can take a tax deduction and offer your employees an HSA — for much less than traditional insurance. If you work for one of the many companies now offering HSAs, chances are your company will help you fund it. And if you're an entrepreneur, you don't need an employer to open one of these accounts.

So if you open an HSA, how does it work? Let's say you deposit $100 per month into your HSA, and your company matches with an additional $100, but you only spend $300 each year on medical expenses. Within a year, you'll have saved $2,139 tax free, at 4 percent annual interest. Within five years, it'll be $11,602. Keep it up, and after 30 years — right about the time you retire — you'll have $121,459 socked away.

And here's the best part: Once you're 65, there's no penalty for dipping into your HSA for any expense whatsoever, not just health-related ones. So in your golden years, you can use the HSA as a tax-deferred retirement account, like an IRA. You can even pass the money on to your children some day.

An HSA could also save you thousands. Buy a cheaper policy, saving hundreds of dollars a month, and put those savings — tax-free — into your HSA. The average monthly premium for an HSA-eligible health plan is around $111. If you are healthy and in your 20s the premium is way lower — you can get a good plan for around $60 per month. Meanwhile, the average monthly premium for an employer-provided plan is $308. So switching to an HSA would save you $2,364 each year in premiums. If you own a business, imagine the savings over a whole group of employees.

And it's your money. You don't have to fork over nearly $200 each month to a big insurance company for services you're probably not really using. How often do you visit a doctor or the hospital anyway: Probably only a couple times a year. You could use that money for routine health expenses and collect interest on what you don't use as you save for a rainy day. And, again, the money you put into the HSA is not taxable.

There's a lot less paperwork involved with HSAs, too. Instead of dealing with co-pays, navigating the terms of what's really covered, submitting forms for reimbursement and wondering how much you'll get back, you just pay out of your HSA. Many of these accounts come with an ATM or debit card, too. So you don't even have to worry about withdrawing money out of the account. Just save your health receipts in case the IRS ever asks to see them.

And you'll find that more medical expenses can be paid out of your HSA funds than traditional insurance plans cover. Contact lenses, dental care, prescription drugs, even psychoanalysis and acupuncture can all be paid out of your HSA.

In fact, that's one of the biggest benefits of these groundbreaking plans: You, not a remote bureaucracy or insurance company, take control of your health care. You decide how your health care dollars are spent. Maybe you're a traditionalist who wants to spend your money on doctor visits and prescription medicines. Or maybe you'd rather visit an acupuncturist and chiropractor. An HSA suits any health care personality.

This return of control to the consumer may be why people with HSAs pay more attention to their health. McKinsey surveyed employees who had HSA-style accounts for a year. The consulting firm found that, compared to their colleagues with traditional plans, health account-holders were 30 percent more likely to get an annual physical and 25 percent more likely to engage in healthy behaviors. And they were 20 percent more likely to follow their doctors' recommended treatments.

The low-cost alternative of HSAs is the biggest change in health policy in decades. High-deductible insurance, already cheaper than traditional insurance, is going down in price all the time. In the last year, premiums dropped 15 percent for HSA-eligible policies. Maybe that's why HSAs are steadily lowering the numbers of the uninsured. One study found that almost 40 percent of individual HSA buyers were previously uninsured. And about half of those signing up earn less than $50,000 a year.

But despite this essentially good news, not everyone can set up an HSA just yet. Some highly regulated states — notably New York and Massachusetts — won't let individuals purchase such plans. An employer can offer them but you can't buy one on your own in these states. That may change: Representative John Shadegg of Arizona has sponsored a bill that would allow insurance companies to sell their policies in any state without being subjected to multiple state insurance bureaucracies. Other states, like California, allow HSAs but impose state taxes on the contributions. Let's hope this changes too.

HSAs have a lot of benefits. And they're the biggest change to hit the health insurance market in years. Seize the HSA opportunity. Because taking control of how you or your company spends health care dollars is just smart business.