East Lyme — Gales Ferry resident Shawn Hysong describes coming back to life like emerging from a lengthy underwater dive.

There's darkness. There's muffled sound. And, in those final moments, there's breathless urgency.

"All I remember is taking a huge breath, and everything snapped right back into focus," the 48-year-old Hysong said, recalling a bustling hospital room and all of the noises that go along with it. "I remember thinking, 'What the hell just happened?'"

It's hard to pick what's most riveting about Hysong's survival story.

It could be that he already was in a hospital room being monitored when he had his heart attack on Sept. 27, 2014.

Or maybe, it's that after the ordeal, he set out to lose 101 pounds — the number that would bring him back to his just-graduated-college weight — and did, in less than a year.

Perhaps it's the odd significance held by Sept. 27: the date of this year's American Heart Association Heart Walk at Rocky Neck State Park, the one year anniversary of Hysong's heart attack, and the same day Hysong's father suffered a fatal heart attack, years ago.

Moments before the Heart Walk began on Sunday, Hysong, his family in tow, was just happy he had the chance to participate.

Last Sept. 27, a Saturday, Hysong was feeling woozy after a day spent working in his yard.

At first, he chalked the off-balance feeling up to a skipped lunch. He ate and took a shower in hopes it would go away.

When it didn't, he found himself in front of a mirror, trying to figure out what was going on.

"You tend to have good judgment when something is wrong with you," Hysong said. "I had no idea (cardiac arrest) was what was going on, but I knew since I couldn't put a finger on the problem — and since the voice inside my head was scared enough — we probably should get it checked out."

Hysong's vital signs plummeted as an ambulance took him to Lawrence + Memorial Hospital and before he knew it — he was having what his 16-year-old son said looked like a seizure.

Then, the heart rate monitor flat-lined.

Later that day, Hysong said, his doctor told him his arteries weren't clogged or dirty. Rather, a small bit of plaque had ruptured in one of them, causing his brain to think his body was bleeding and cause a blockage while trying to fix the problem.

The doctor "said 'You're almost perfect, but we think you could lose a little bit of weight,'" Hysong said. "I said, 'OK, I am going to lose it.' In exchange for them bringing me back to life, that's probably the least I could do."

In the months since, he's dedicated four to five days a week to carefully conducted exercise and has altered his diet with the help of two rehabilitation programs: one offered by Lawrence + Memorial, and another run by Electric Boat, his place of employment.

"Last year at this time, I was 326" pounds, Hysong said. "I knew I was heavy, but I could do anything I wanted."

"Now that I've lost all this weight, I'm starting to realize cutting the grass takes 30 minutes less ... and the lawn didn't get any smaller," he continued. "I don't think I was fooling myself, but I got too comfortable with what was acceptable."

Michael Hamilton, outgoing Heart Walk chairman and vice president of resort operations at Mohegan Sun — a long-time sponsor of the event — said he frequently learns of people's heart-related stories.

"We hear a lot," he said. "Sometimes we hear good stories that are awesome like (Hysong's). Sometimes they're not so good."

Hamilton said he hopes the more than 1,000 attendees who showed up on Sunday's brisk but beautiful morning, many in groups donning matching T-shirts, embrace the reason they came.

"Hopefully, people just start to look at things a little bit healthier, take at least one step to get a little bit healthier," he said.

Going forward, Hysong — who said the Sunday walk, while an emotional time of reflection for his family, was physically "easy" — wants to continue doing that.

In January, he'll begin to split his time at the gym between cardio and strength training, his eyes set on a new goal: completing a Spartan obstacle race next year in August.

"You can't control everything — we could be in an accident tomorrow," Hysong said. "But the stuff we can control is certainly worth controlling."

l.boyle@theday.com

Twitter: @LindsayABoyle