You'll find Bob Haspel at the Home Depot in Columbia almost every weekday morning, just after it opens at 6 o'clock.

He starts in the lumber department, then makes his way past the gutters and the roof cement and the all-season doors, down through chainsaws and lawn equipment and around again to the spot where he started - only to circle the perimeter of the 90,000-square-foot store two times more.

Haspel is not shopping, or searching for an obscure bit of hardware amid the mass of merchandise. He is walking.

His cardiologist told him to - 30 minutes a day, a few times a week - to get in shape for the heart transplant he is awaiting.

"After the third day in there in a row, one of [the employees] said, 'Sir, can we help you?'" explains Haspel, 46, who has a pacemaker and defibrillator in his chest. "I said, 'Actually, no. I'm in here, doctor's orders, walking. I really don't care to go to the mall.'"

Haspel is not a mall kind of guy; he wears old sweat shirts and flannels and red-and-gray sneakers that are not brand-name. Besides, for some reason, walking at the mall hurts his knees and lower back.

But, really, he just likes the smell of the lumber at the Home Depot, and feels more comfortable among the power tools and electrical wire. Haspel worked as an electrician for 27 years before heart problems sidelined him in May.

"It's more like I'm in my own surroundings," says Haspel, who has a Harley Davidson motorcycle he still rides from time to time.

Almost every morning, Haspel, a Columbia resident, gets up about 5 o'clock, watches the news and takes his wife, Cindy, to catch a bus to her job as a paralegal for the Securities and Exchange Commission in Washington. Then he heads to the Home Depot off Snowden River Parkway. He parks as far from the entrance as he can (as long as it's not raining). Sometimes he walks through the shopping center parking lots - empty at that hour - to get in an extra 15 minutes of exercise.

After three perimeter laps inside, he takes to the aisles, moving through plumbing and paint and flooring.

"I go through the electrical department quite often just to see some new products here and there," Haspel says.

He doesn't walk particularly fast. His doctor said the point isn't to win a race, it's to keep his weight down and get him in shape for the transplant. Two years ago, Haspel was carrying 254 pounds on his 5-foot-11-inch frame. Through exercise and watching what he eats, he now weighs about 210.

In 1996 - on the weekend Haspel turned 40 - doctors diagnosed his mild case of cardiomyopathy, a weakness of the heart muscle that in some cases leads to heart failure. Medication kept the problem under control until winter last year, when he started waking up in the middle of the night out of breath, and could feel himself growing sluggish at work.

By March, his condition had worsened enough that his local cardiologist, Dr. Michael E. Silverman, suggested that he go to Johns Hopkins Hospital to be evaluated for a potential transplant.

"I was like, 'You gotta be kidding me.' It was like a ton of brick just hit me," says Haspel, a West Virginia native who has two daughters, ages 15 and 20, and an 11-month-old grandson. "I was like, 'Aw, man, it's over.'"

He had reason to be scared, and not just because his Uncle Johnny died of heart failure at age 37. About 10 years ago, Haspel's 13-year-old nephew received a heart transplant in Alabama. He didn't survive.

Started walking

Silverman urged Haspel to start walking, which he did - sometimes outside with a neighbor, with whom he had trouble keeping pace.

By late May, he found himself at the emergency room again and spent a week at Howard County General Hospital. His doctors ordered him off the job.

Haspel concedes that he had become a danger to himself and others - he did a lot of work on ladders - but was crushed by the thought of having to sit at home. For the next two months, that's basically what he did. Depressed, he worried about finances and how to pass the time.

Once his disability checks began arriving, Haspel started feeling more upbeat. He began walking more frequently. Because the late summer days were hot, he wanted to find a place to walk indoors. His wife suggested the mall; he went to the Home Depot instead.

A lot of the employees there recognize him now, the man with the "Medic Alert" hanging on a chain around his neck. One worker calls him "The Inspector," as if he has been sent by corporate headquarters with a clipboard and checklist to make sure everything is in order. By coincidence, one of the assistant managers, John Badger, 55, sees the same Hopkins heart specialist, so he and Haspel compare notes on medications and operations.

When someone asks him how he is doing, he replies with a smile. "Still vertical this morning," he says.

Called a model patient

Haspel has been feeling much better since early September, when doctors at Hopkins implanted his pacemaker. For his irregular heartbeat, he was given a defibrillator to shock his heart back into a normal rhythm if it starts to race. Without it, he could die.

Silverman calls Haspel a model patient, diligent about taking his medication, forgoing the bacon he would love to eat for breakfast and strengthening his heart muscle through walking, as others strengthen their biceps by lifting weights. Not all of Silverman's patients take care of themselves so well.

"There's nothing more I can ask of him," says the cardiologist. "He is stacking everything in his favor."

Haspel likes walking at the Home Depot, though.

"I think just getting up early and getting out keeps me motivated," he says.

He gets ideas for home improvement projects along the way and, sometimes, at the end of his walk, buys something. One of his last purchases was an electric screwdriver.

He also has learned quite a bit about the store on his daily rounds: that it's not a good idea to walk behind the fork lift when it's beeping, that duct tape can be found in more than one aisle, and that all the displays power up every morning at 7:05.

Occasionally, customers who see his "Home Depot Pro" hat - a recent gift from one of the employees - ask him for help finding something.

Haspel is always reachable by cell phone, in case he gets the call saying doctors have found him a heart (it could take up to two years). He knows not to keep the phone in his left breast pocket, where the signals might interfere with his pacemaker and, he says, "shut me off."

"Day at a time," he says of his outlook on life. "That's all you can do."