When we diet for our families, the purpose is to get ourselves in better shape so we can be the best spouses to our husbands or wives and the best parents to our children.

"All you need is love" might be the mantra for the new "eat-half" diet. By undertaking disciplined eating for your sweetheart instead of doing it for yourself, you increase your chance of success.

But the Half Diet Diet will still not reach its full potential for taking weight off and keeping it off unless one more habit is added, and that habit is-you guessed it-the exercise-habit. We are in Australia as we write this article, and it seems like the perfect setting. Are there any people in the world more active, more into fitness, and more outdoorsy than Ausies? We doubt it.

And the fact is that while putting less (and better) food into your body is going to make your body work better, you still have got to make your body work!

Should it be a chore, a task, a constant struggle to force this work to happen-to force your body to exercise? Does it have to be something you hate doing but keep motivating yourself to do anyway for your own good, like taking cod liver oil?

No! Exercising, like eating, should be one of the natural and simple and pure joys of life. It should feel good while you're doing it as well as when you're through, and it should be a way of rewarding yourself, not a way of punishing yourself.

The key is to find a form of exercise that you love, one that makes your body smile while it's sweating out that pore-cleaning water and pumping those endorphins around through your expanded lungs and your healthier cardiovascular system.

For me, Richard, it's tennis. It used to be basketball, but now it's tennis: hard tennis singles, without breaks between games, so that it's aerobic. For my, Linda, it's the bike: the road bike if the weather is good, the stationery one at home if it's not. For one of our daughters, it's running; for another daughter, it's hiking. For a good friend, it's the aerobic yoga class at the gym that has a good nursery for her two preschoolers. For another friend, it's the StairMaster while he reads the morning paper every day. For yet another friend, it's early-morning lap swimming.

What we're saying here is simply that you've got to find or develop a physical passion of some kind-a form of exercise that you love. You don't need to instantly love it. It can take a little time to get into something, to get good enough at it that it's enjoyable, and to get hooked on the way it makes you feel. If you don't know what your physical passion might be, start trying things until you find one.

The point is that we all need an "output" to go with our improved "input." Disciplining ourselves with regard to input into our bodies-less and better food, eaten more slowly, and more water-has to be accompanied and enhanced by the passion and rigor of the output of our exercise. One side is working on the quality and quantity of the calories we put in, and the other side is developing the most enjoyable and beneficial way of burning and sweating them out!

The very best kind of exercise habit is one you can enjoy with your family. Families who have a favorite sport, one that they enjoy together, gain the win-win, double benefit of physical improvement and emotional improvement. It's all been said before: "The family that plays together stays together."

If you are a skier, you will be motivated to get more in shape and stay in shape for skiing with year-around exercises or a ski-like elliptical machine. If you are a tennis family (like we are) you will play more often with others to become better for when you play with your family. If you run together with your sweetheart, swim together, hike together, bike together-whatever it is, it will help you both with your exercise habit and with your family's communication habit.

Then, put these good habits together with the water habit, the slow habit, and the eat-half habit from articles one and two-and you will find that all these positive addictions will begin to work together for the benefit of your partner, your lover, your sweetheart as well as the benefit of your body!

_Note: This is the third of four articles in the "Sweetheart Diet" series. Read part one and part two.