If you’re a Millennial, you will likely have to finance retirements that are actually longer than your working careers. If you are in this group, you may not be thinking much about retirement, but here are three things worth knowing about saving for retirement — now.

1. You won’t be able to work as long as you think

You hear people talk about 65 as the “normal” retirement age, even though it’s no longer that, even for Social Security benefits. Oddly, considering all the talk you hear about people retiring later, the average age at which U.S. citizens report retiring is 62 — and the Employee Benefit Research Institute’s Retirement Confidence Survey has consistently found that a large percentage of retirees leave the workforce earlier than planned — 46 percent of them in 2016, for example. Many who retire earlier than they had planned often do so for negative reasons, such as a health problem or disability (61 percent).

So, if you’re thinking you don’t need to save for retirement now because you can you just keep working … well, you might need a “Plan B.”

2. You could be missing out on “free” money

You may not be saving at all (not to worry, your parents got off to a slow start as well). But if you do have a 401(k) or other retirement savings plan at work, you may also have something called an employer match. That’s where your employer will put into your account a certain amount, perhaps 50 cents for every dollar you save. For you, that’s “free money,” but you’ll only get that if you actually take advantage of your retirement savings plan at work.

3. The sooner you start, the easier it will be

The Labor Department says that for every 10 years you delay before starting to save for retirement, you will need to save three times as much each month to catch up.

I know it sounds simplistic. But trust me, you’ll be amazed at how quickly your retirement savings grow. See, the money you save earns interest. Then you earn interest on the money you originally save, plus on the interest you’ve accumulated. As your savings grow, you earn interest on a bigger and bigger pool of money. This is something financial pros call the “magic of compounding.” But it’s no trick.

Nevin E. Adams, JD, is Chief Content Officer for the American Retirement Association, a non-profit professional organization established to educate all types of retirement plan professionals, and to preserve and enhance the employer-based retirement plan system as part of the development of a cohesive and coherent national retirement income policy.