It started because of money. Not for me, the candidate, but for my college children, who always need cash.

"What do you mean, you're betting on me?" I said last fall when they asked me to run a six-mile marathon this spring.

"We need a new stereo," my oldest son said. "You're our only hope."

"That's the craziest statement I ever heard," I said. "What happened to your summer job money? Anyway, I'm too old to run in a marathon."

"We know," my daughter answered. "That's why we'll win our bets. None of our friends I'll believe you can even finish the course, much less place in the top 50."

"I don't think she can run the course," the youngest said in a voice I wasn't intended to hear.

"They'll think we have to bet on you because we're loyal to our mother," the oldest added.

"And what do I get?" I broke into this flattering exchange.

"You get a T-shirt," my daughter said. "Boone Bell gives them out. I think they're blue."

"A T-shirt? One that says 'This Person Has Completed a Marathon'?"

They nooded. I put on my sneakers.

"It won't hurt to get myself in shape," I said. "We'll talk about the betting part later."

I hated myself, of course. How could I care so much that I might be like one of those girls in the ads, running with her hair blowing in the wind? But I told myself it was lucky I had discovered my children's awful commercial values. Arguing with them now would be useless; only a display of my own descipline and sportsmanship would teach them one of life's real values: they joy of doing something purely for the sake of doing it well.

Their training plan was simple. They would leave for their colleges, and I would run every day.

"All you have to do is increase your speed and distance each week, and we'll do the rest," they said.

'We'll do the rest indeed,' I thought as I toiled up and down the hills.

Dogs barked as I puffed by. Neighbors looked away from my dripping body. I was pleased that I wasn't having a series of heart attacks, but I was too preoccupied mentally to do more than note in passing that the leaves were turning red and gold and then falling, and week by week the hills were getting easier. I was having constant inner dialogues with my children.

"Your sort of outlook is why Rome fell," I said to them in my mind as I ran. "The sports world is growing more and more corrupt, and all because everybody is in it for the money. Now even jogging, the metaphysical sport, is about to become money oriented. And by you, my own children!"

My daughter came home in late October - she got a ride with a friend to save money - to start me a wind sprints. She led me along MacArthur Boulevard and down the hill to M Street, where going east the path is six inches wide and the cars coming at you are eight inches to your right. It was not a very good place to talk about values.

"I might slip," I screamed plaintively, "and be killed."

"Just watch where you're going," she called back.

"The fumes are awful," I shouted.

"When your wind gets better they'll seem worse," she said.

Then she shot straight up the Exorcist steps and ran around the block while I slobbered behind, and we started off again, through the Georgetown campus and up Glover Archbold Park, where the uneven footing was good for strengthening ankles. I was puffing too hard to say a word.

I thought I might do better with the boys. I pictured nice little talks while we were running ("Always run at a speed that is comfortable enough for conversation." - Joggers' Manual). But at Thanksgiving - they hitchiked home to save money - they decided to extend my distance. All I could do was pant while they paced me with their 10-speeds, playing their radios and talking only to each other. Once in the woods, I tripped and fell and they rode on, oblivious, out of sight in the trees. "Hurry up," I heard their voices call back. "You're much too slow for November."

But then they came back, and the oldest helped me up, tempered with the advice that "You can't fall down in a race. You might hurt something and have to quit."

Christmas would be the moment, I was sure. A sentimental holiday devoted to family and enduring ideas. But there never seemed to be any time to talk; they had gotten selling jobs to buy my Christmas present, an electric-green running outfit with green suede shoes to match and a thick, green wool hat to keep out the cold and snow. Before I knew it they had left again, for the winter term.

"We'll write to keep you going," they promised.

Long letters came, careful treatises on the fine points of running: how to handle crosswinds, what to do about heel shock, Hitting the Wall, and Third Wind. They sounded harassed; they had had to get school jobs to pay for my new down vest. For me it was a lovely January, complete with laughing children and snowballs, and crystal flakes that spun under my flying feet like clouds.I didn't even get my usual winter cold.

By now I was on grape juice and yogurt and gorp and no coffee except in the morning, and I took to waking in the middle of the night, so ful of energy that I sat up and talked to myself. They wrote that this meant I had reached a plateau and I could, should, increase my speed and distance even more. By February neighbors started waving, and I was going back steadily to the alteration lady, as flab and inches peeled off everywhere below my waist.

"You'll have to pay her bill too, out of your salaries," I asserted myself at Valentine's Day, and when they agreed to this and sent me a box of health-food candy it gave me pause. Did they actually think I was going to be able to run well in this race? It looked that way, because for Easter they gave me a pair of neon satin running shorts, with my own initials on one side. They seemed genuinely proud of the way I looked; they even took my picture. We tested the shorts on a warm day on a long run along the twopath, and we were all happy with my progress. In fact, we were having such a good time running that I hated to give, at last, my lecture.

When I had finished they seemed dewyeyed.

"I guess we won't bet our friends after all," my daughter choked. "Our jobs have got us enough money, and it does seem dishonest - no one has any way of knowing how good you've gotten."

I didn't blink. "I'm proud of you," I said.

"You've made the right decision. When I'm running the race you'll be truly pleased that it's just your mother doing it, and not a cog in a parimutuel machine."

"Right," the youngest said. "After all, what's the total loss of stereophonic sound compared to our family's honor?"

I ignored the catch in his voice and drove them all to the bus station for their trip back to school, instead of making them walk. And I reflected that as the time approaches - the race is this Sunday - it is morally satisfying to sense thay they are getting nervous about my condition, not about mere money. They keep writing to ask how I'm felling, and once they even phoned, not collect, to suggest a final medical checkup. But I don't really need one. My running distance is up to five miles, and as I labor on I am beginning to dream not only of placing high in the race, but even of setting a good time. And there is something else. At a party the other day, with no more need for secrecy, I mentioned to a male friend that I was getting ready for a 10,000-meter race. He burst out laughing.

"Someone as fragile as you?" he said. He is polite; he meant old and scrawny.

"I don't think you could finish a course like that without hurting yourself," he added in a kindly tone. Suddenly my mind began to spin. I saw the blue T-shirt, of course. But I saw, wonderfully, much, much more. Dresses, weekends, even a new car floated into my Technicolor view. I looked at him tenderly, and then I leaned forward.

"Would you like to bet?" I said.

Ms. Hass, a local jogger, is planning to enter the mini-marathon. Anyone wishing to place private wagers may contact her at the starting line. She can be recognized by her canary-yellow-and-bright-purple running shorts and her orange nylon shoes. BONNE BELL'S BONNY BELLES

The Bonne Bell 10-kilometer race, for women only, is being organized by Washington RunHers Unltd. It will be run Sunday morning at 8, starting at Hains Point. You can enter as late as Saturday night, through, at Stouffer's National Center Hotel, 2399 S. Jefferson Davis Highway (Route 1), Arlington. There'll be someone there to register entrants between 9 and 9. For more information, call Henley Roughton, 780-8228.