No matter how young you are, it's never too soon to learn to make realistic New Year's resolutions. Here's what some fourth-grade and fifth-grade students in Arlington said last week they have determined to do in 1991:

"I resolve to clean my room at least once a week."

"I'm going to get all A's on my report card."

"I've decided to make the soccer team."

"I'm positively going to practice piano."

"I'm going to get some exercise every day."

"I will go to bed earlier on school nights. Maybe then I won't fall asleep in math class."

Some other kids in those classes made resolutions about what they're not going to do.

"I'm not going to eat as many potato chips."

"I promise not to yell at my brother so much."

"I'm not going to watch so much TV."

"I'm never, ever going to smoke cigarettes. Not in 1991, or any year."

Those are all good resolutions. And several of them will help keep the kids who made them healthy. You can probably figure out which ones. Give it a try.

You're right -- the kids who promised themselves that they would exercise, eat sensibly, get enough sleep and avoid smoking cigarettes made healthful decisions for 1991. Regular exercise, good nutrition and lots of rest are the basic ingredients for staying well.

Look at that last resolution, the one about smoking. The boy who made it is 10 years old. As long as he can remember, he has known about how bad cigarettes are. He has heard it from his parents and his teachers and his basketball coach. He has read about it in books, magazines and the newspaper. And he's convinced.

The trouble is, a lot of kids aren't convinced that smoking is bad for them. This is especially true of teenagers. According to the American Academy of Pediatrics, an organization of children's doctors, more than 3,000 teenagers become regular smokers every day in the United States -- that's 1 million teens every year.

There's been a slight decrease in the number of teenage boys who smoke. But there has been an increase among girls who smoke. Today, 20 percent of high-school senior girls are regular smokers, compared to 16 percent of high-school senior boys.

It all adds up to about 6 million American teenagers who smoke. And there are also 100,000 children ages 10 to 13 who smoke.

Smoking is dangerous at any age. But it's especially bad to start early in life, doctors say. The younger people are when they start smoking, the more likely they are to die of lung cancer. Smokers who start before age 15 have cancer rates 19 times higher than those of nonsmokers.

In the U.S., 350,000 people die every year from illnesses related to tobacco. They die from heart disease, cancer or lung disease. Doctors believe that if everyone who smokes quit today, there would be 90 percent less lung cancer, 50 percent less bladder cancer and 33 percent less heart disease.

The government has many ways of regulating smoking. Last year, for example, schools in California, Tennessee, Utah and Virginia added a smoking unit to their health curriculum. Iowa, New Hampshire, Rhode Island, South Carolina and Virginia required "smoke-free" public areas in restaurants, on buses, in malls, hotel lobbies, laundromats and other places where people gather. Minnesota banned cigarette machines from areas where people under 18 can go.

In the District and in Virginia, it's illegal to buy cigarettes if you're under 16. In Maryland, it's illegal if you're under 18.

So smoking's hazardous to your health. If you're a minor, it's illegal. And it's expensive, too. According the U.S. Department of Health and Human Services, teenagers buy 947 million packs of cigarettes and 26 million cans of smokeless tobacco every year. The price tag? More than $1 billion!

So why do kids start smoking? Well, if your parents do, you're more likely to try it, too. Peer pressure also plays an important part in making the decision to smoke. The usual reason: "It's cool. It makes me look grown-up."

But not all kids think it's cool to smoke. An American Cancer Society survey showed that more than three quarters of boys ages 12 to 17 said they didn't want to date someone who smokes. Girls were more willing to tolerate smoke, but not by much. Sixty-nine percent said they'd rather date nonsmokers.

The Arlington fifth-grader who resolved not to smoke in 1991 or any year made a smart decision. He'll never become addicted to tobacco. He'll never crave cigarettes or feel nervous without them. He'll reduce his chances of getting serious illnesses such as heart disease and cancer. And he'll save a lot of money.

So what's your resolution for 1991?Tips for Parents

The American Academy of Pediatrics is offering the public a new free brochure, "Smoking: Guidelines for Teens," as well as a state-by-state listing of tobacco legislation and age restrictions. Write to: Teen Smoking, Dept. C, American Academy of Pediatrics, P.O. Box 927, Elk Grove Village, Ill. 60009-0927. Catherine O'Neill is a children's writer.