GRAND BAHAMA ISLAND -- Though some people might debate whether Columbus landed on the Bahamian island of San Salvador or the Bahamian key called Samana, none of us would argue that he landed in the Bahamas and was greeted by the Lucayan Indians.

The Bahamas, of course, is planning a pretty big party in l992 to commemorate that landfall, but our island isn't waiting until then. Since the Lucayan Indians also lived here, the American Embassy in Nassau and the Grand Bahama Port Authority this week sponsored a superb series of lectures entitled "The Lucayan Indians at the Time of Columbus." A lot of busy people stopped their normal routines to learn about our island and these gentle Indians. I attended, too, and was fortunate enough to sit by several very interesting people, particularly when it comes to exercise, eating and adventure habits, starting with U.S. Ambassador to the Bahamas Carol Boyd Hallett and her husband Jim. The Ambassador is 5 feet 4 inches tall, weighs 120 pounds, has brunet hair framing a face that likes to smile and has the tight, smooth skin tone of a 30-year-old tennis player. She turned 50 on Oct. 16. Jim Hallett, 50, is 6 feet tall and, at 150 pounds, is as slender as a fishing rod. His smile is quick, too, and it's most pleasant to watch how these two people enjoy both their lives and one another.

At six one morning, I joined them for a one-hour sunrise walk along the back roads and beaches near the Xanadu Hotel. The Halletts walk fast enough to put blisters on my feet, and they do it for at least an hour each day when they are away from the ambassador's residence in Nassau. Six years ago, Jim Hallett started their program, which included major changes in their eating and exercise habits. He then weighed 190 pounds, and says he looked just like the former me, an awfully brave thing for anyone to say.

Back then, he also had a cholesterol problem. He says it once went to 300 mg/dl, a very dangerous level -- 200 would have been considered normal. And over the years it decreased to that safe level as his weight dropped, his eating habits improved (he says cutting out desserts was the most important change) and his exercise increased.

In addition, Hallet started having regular tests on a treadmill, since his family had a history of high cholesterol and heart disease. Each year, he did better on his tests and each year he felt better, too, until last Dec. 29. His stress test in Nassau was a little irregular. In Miami the next week his stress test was very irregular.

After further tests, this very thin man who had exercised and eaten right for six years went in for quadruple bypass surgery. The moral here is a very important one: Don't assume your heart is okay simply because you've been good for a number of years. If you are more than 40 years old, or from a family with a history of high cholesterol or heart disease, or were bad for a good portion of your life, think about a stress test.

The operation certainly hasn't slowed Hallett down when it comes to being active. Each morning, he and the ambassador arise at 4:40 in the embassy residence. They dress in workout clothes, stretch for 15 minutes in their bedroom and then walk downstairs to a separate building, a gazebo, which is now their gym. The gym equipment, along with five cats, flew with them to the Bahamas. The ambassador piloted the plane.

For five minutes they warm up (pedal slowly) on twin stationary bikes, then take their heart beats up to their recommended exertion levels for a full 30 minutes and then cool down (more slow pedaling) for five minutes. Their workout music varies from classical to Herb Alpert to country and western.

Two or three days a week, the Halletts do strength work on their weight-lifting machine and on a rowing machine, and every single day they think about what they eat, starting with breakfast. Carol Hallett eats brown rice with crushed walnuts and raisins, and Jim Hallett eats a mixture of oat bran, oatmeal, raisins, nuts, shredded wheat and skim milk. They fix their own breakfasts, too, and I hope you'll be as creative.

This afternoon, The Halletts spent about 45 minutes with our dolphins. While Jim Hallett swam with them, the ambassador and I sat with our feet dangling in the water. And though it's probably a very bad breach of protocol, I must tell you, our government's representative to this country has an amazingly well-kept pair of legs, thanks, I am sure, to her balanced program of exercise and clean and godly living.

I did not get to see the legs of Doreen de la Rue and her husband Don, but I'll bet you both pairs are equally as conditioned. For 30 years, Don de la Rue has been the financial manager of the Grand Bahama Development group of companies (there are many) that are about as important to our island as the federal government is to the District.

The de la Rues are in their mid-fifties, and though they are both quiet in their public presentations, I found them to be very adventuresome.

Four years ago they decided to take up trekking. If you are not familiar with the sport, it's essentially walking with a long-distance destination in mind, and the more exotic the destination the better.

Like trekking through Nepal. The de la Rues have been there twice. On their first trip, they spent a week walking from Pokhara through the foothills of Annapurna. In this instance, "foothills" means they walked to only 11,000 feet. On their second trip, they walked for three weeks from the Nepalese village of Kirantichhap to the 18,000-foot high Japanese base camp at Mount Everest. Only four trekkers were on the three-week trip, but 15 Sherpas and porters traveled with them to set up camps, provide meals filled with vegetables, yak meat and chicken, and generally make the trek effortless except for the walking.

Two things really interested me about these Nepalese treks. They didn't require traumatic physical conditioning (the de la Rues walked a lot for three months before going -- their only real preparation), and they really aren't that expensive compared with other places you might spend time.

Two weeks at a nice health spa can easily cost $3,000 per person; two weeks in intensive care at a hospital (where people who don't respect their health may end up prematurely) can cost up to $20,000 per person. But 15 days in Nepal, including hotels, eight days of trekking, and round-trip airfare from New York, can cost less than $2,600 per person. I can assure you the exhilaration provided by the unearthly beauty of the top of the earth is much more enjoyable than these other options.

When I was 20, long before thoughts of mortality had any meaning to me, I spent a wonderful 10 days in Katmandu, Nepal, representing my school, the University of the Seven Seas, in meetings with King Mahendra. Then I was much more interested in the palaces and great temples and saw the mountains only as an incidental backdrop to my visit.

I would like to go back there now for a closer and more active visit with the mountains, and I think I know two couples who would be fun to go with.