The physical effects of a healthier heart extend to emotional well-being, Squires said, and that's a crucial component of recovery.
"Telling patients that they don't have to "baby" themselves," he said, "they can actually push themselves harder -- I think it improves their self-reliance, their confidence."
After her heart attack, Marofske was nervous about working out. She could barely walk up a flight of stairs. She had fallen out of the habit of exercising years earlier, and before the heart attack, the only thing she did that came close to exercise was walking her dog.
Now she leaves her cardiac rehab sessions feeling more confident. She has joined a gym. And for fun, she and her husband ride a tandem bicycle.
"I wasn't expecting to be able to do the level of workout that I'm doing now," she said. "I'm really pushing myself.
"There is no cheating," she said, laughing, since the heart monitors she is hooked up to at rehab would give that away. "I work up a pretty good sweat. I feel really good."