Q.My 15-year-old son -- a good kid and a mediocre student -- is just not motivated.

His dad died when he was 8, his relatives live far away, he's lost interest in Big Brother activities, and he says he doesn't even want to go on summer vacations with his sister and me anymore.

He also seems to need a lot of time alone. If he's not with his friends -- he has several groups of them -- he plays video and computer games or works out with his weights and his exercise equipment. I get so caught up in his little sister's activities and her needs that I sometimes forget to notice that he has been playing video games for hours.

This summer he is only working as a camp counselor for two weeks and reading two books for school, although I'm sure he will mow the lawn if our house looks untidy because that embarrasses him.

He will do other chores but only because of the carrots I offer. Since he is saving for guitar lessons and a car, I pay him for his work, but I still must meet his price and give him much advance notice. He also procrastinates a lot, intending to do his chores "later," but when his buddies come by, he's gone!

How can I get my son more involved? He is bigger and stronger than I am and I think he obeys me only if he wants to.

A.Most children are pressured to do too much these days, but some, like your son, aren't doing enough.

Of the two, he may be on the safer track, for it is often better to do too little than too much, especially now. Your boy is in a greedy age when his appetite for food and sleep and self-satisfaction is almost limitless, and this leaves him with little time or energy to spend on others.

This stretch lasts two to four years, affects all teenagers -- to a greater or lesser degree -- and should encourage parents to look at their youngsters in a fresh way.

You'd be smart to start with a medical checkup for your son -- to make sure he's not depressed -- and then to change some family rules. He may be bigger and stronger than you are, but remember: You're in charge. You buy the food. You call the plumber. And you pay the mortgage.

Your son can't do these things yet, but he can help out around the house and he should do it without charging you for it.

A family is a team, not a business, and every member should pitch in, not because he likes to do chores, but because the chores must be done.

You might pay a child to clean out the garage so he'll have extra money to spend on his class trip, but you shouldn't pay him for taking out the trash, any more than he should pay you for making his school lunches.

You do have to pay your son in appreciation and respect, however, and you also have to teach him how to do his work quickly, so he'll have more time to play video games; to do it well, so he won't have to do it all over again; and to avoid some parental nagging by doing his chores within an hour after he's promised to do them and by telling you as soon as they're done.

Before you announce the new rules, write a list of all the household chores that must be done regularly -- so your children can see why they must do their own laundry and some light housework every week -- and then ask them to do one extra job every week completely on their own, so they will find that there is creativity in housework, as there is everywhere.

If your son decides to cook dinner every Monday, for instance, let him decide what to cook, how to cook it and how to clean up the mess he's made. As long as you praise him freely, his cooking will improve and so, in time, will his disposition.

If your son won't do any chores without being paid, however, keep your mouth shut and your wallet, too. You aren't required to give an allowance to a 15-year-old or buy him a new backpack for school -- or let him get a learner's permit. If a teenager isn't mature enough to do his share around the house, he isn't mature enough to drive a car.

Questions? Send them to advice@margueritekelly.com or to Box 15310, Washington, D.C. 20003.