Face it. You only have one heart, so take care of it. So say the folks at the American Heart Association. For that matter, so says your doctor, your mama, your aerobics instructor and just about anybody with the slightest interest in your health. This week, the AHA kicked off a HeartFest campaign to encourage shoppers to choose low-fat products and to practice other healthy habits. To do this, they've set up information booths in more than 6,000 grocery stores across the country. In the Baltimore area, that includes 51 Giant and 23 Safeway stores, says AHA spokeswoman Lora Hillgartner. "With all of the low-fat and non-fat products on the market today, it's easy to simply substitute low-fat varieties [of foods]," says Rosalind Trieber, HeartFest chairwoman. "But with the new label requirements, these terms cannot be used unless the product meets legal standards set by the government." To help consumers understand what these terms mean, the AHA kiosks will be stocking brochures explaining the new food labels required by the government. Shoppers also can get coupon books (which include a quiz on fat consumption) from AHA volunteers. And periodically during the week, American Heart Association volunteers will staff the kiosks to answer questions. Volunteers will most likely be at all of the kiosks on Saturdays, the busiest shopping day, Ms. Hillgartner says. But the most important steps toward good health are self-initiated: Even though we've heard it many times, the edict to eat more vegetables, grains and cereals is still a heart-smart practice, she says. The other two biggies for pro-active heart care: Stop smoking and exercise, says Dr. Kerry Stewart, associate professor of medicine and director of the cardiac rehabilitation program at Johns Hopkins University. The good news, according to Dr. Stewart: "It is never really too late to start."