I work with computers, and as a result I sit a lot. As you age, an old rule comes forcefully into play: Use it or lose it. And from my early 70s on, I lost my physical fitness. Then came the onset of type 2 diabetes and gouty arthritis.

One day I was taking a bag of groceries out of the car and strained my back. I figured that in a few days the discomfort would go away, but it didn't. And when my doctor X-rayed my back, I learned that I had a pinched sciatic nerve. Ouch!

Imagine my surprise when physical therapy and heat treatments healed my sciatic back. Then, just before Christmas, I tripped while leaving a restaurant, fell, and broke my right shoulder. Back to physical therapy.

However, I had no stamina and was barely able to hobble around. I actually had to ride one of those electric carts around the grocery store. I stood 6-foot-2 and weighed 245 pounds. That is obese.

Right about that time, the new Life Time Fitness was nearing completion in Lenexa. At my daughter's insistence, I went down and signed up for a personal trainer. Mine is Lais Pyfrom, who on the first day ran me through some tests, which showed that my body strength was equal to someone five years older than my actual age. Boy, was that a wakeup call.

Lais (pronounced Lace) is 24 years old, about 5 feet tall, weighs about 120 pounds, and is fit, lean, and mean. She pushed me, gently but firmly. She would say, "You have to feel it a bit; otherwise you are not improving." No pain, no gain.

The process of becoming fit requires commitment. I have never been much of a physical fitness freak; I was naturally blessed with good health, and most of my life I have been pretty fit. But the aging process changes the game, and eventually you have to work at it to keep fit. I am not there yet. But my weight is down to 224 and my stamina is now such that last week I walked through two grocery stores, a hardware store, and a big Costco and came home and put all the stuff away before I had to sit down and rest. That was a huge step forward.

What do they do at a fitness center to yield those kinds of changes in just a little over four months? It takes some testing, some learning, and a personal trainer like Lais to push you from time to time. When I started, I barely made it through 20 minutes on the treadmill at low settings. Now my typical exercise is 35 minutes at high intensity and occasional exercises lasting over an hour. The weight training has gradually brought flexibility back to my right shoulder. And the funny thing about all this is that I am really enjoying the daily workouts.

Let's look at some of the practical things I've learned. First, I took a "calorie point" test, which tells you exactly how many calories you need each day to maintain your body healthfully. Everyone is different, and to measure your weight loss properly you have to count calories.

Next I bought a heart monitor, which measures your heart rate as you exercise and tells you when you are pushing too hard or not hard enough. At the end of the workout, mine reports how many calories I've burned.

After that, the "cardio point" assessment tells you what your maximum heart rate should be. A relatively low heart rate burns the most fat, so a low-intensity workout for a longer time is more effective. Surprised? I sure was. Smart workouts are more important than hard ones.

Years ago at my business we used to give employee surveys, and one of the questions was, "What do you consider most important in your life?" We got all kinds of answers, but my assistant used to look at the results and say, "What's the matter with these people? Don't they know that health is the most important thing? If you ain't got health, you ain't got nothin'!"

Exercise actually makes you feel better, and it improves your attitude about yourself. If you are a couch potato, you need to get moving! The route I took was not cheap, but good health is priceless, so I feel it was worth every cent.

Lais' attitude and encouragement is both a guide and an incentive. I hardly ever go into the gym without having her take a look at what I'm doing. She'll then give me some encouragement, or say, "Go up to 16 pounds; you are way past swinging a 10-pound weight. Go for it."

So I do, and I am hoping you will, too.