There’s no better way to test-drive a heart than to run a marathon. Anna Borghesani, a 41-year-old scientist and part-time fitness instructor from the United Kingdom ran the 2014 London Marathon just 15 months after open-heart surgery.

Immediately upon entering this world, doctors didn’t think Borghesani, who was born in Italy, would survive. Because she had pulmonary stenosis, a congenital heart defect , she didn’t even have the strength to cry as a baby. So, she had her first open-heart surgery at three years old to enlarge the narrowed pulmonary valve.

The surgery allowed her to have an active childhood, in which she could often be found running, cycling, swimming, diving and skiing.

Life was moving along. She got married and had a daughter of her own. However, shortly after becoming a mother, her heart started failing her again, so her cardiologist recommended she get a brand new pulmonary valve.

“…The week before the operation, I was absolutely terrified, as I knew they’d stop my heart from beating and use a heart-lung machine to circulate blood around my body during the operation. The surgery went well, but the psychological stress was immense,” Borghesani wrote on Women’s Running UK. “Given it was open-heart surgery and that the surgeons had had to cut through my breastbone to reach my heart, the pain I felt in my chest afterwards was almost unbearable. With every breath I had to breathe against the pain. I was constantly breathless, felt incredibly weak and couldn’t sleep. It was a nightmare. Eventually I became depressed, as the light at the end of the tunnel looked so dim.”

To help get her through those dark days, she set a goal for herself: Run the 2014 London Marathon, a race due to occur a little more than a year after her second heart surgery. She picked up running while she was in college, and made it a part of her weekly fitness regimen.

She was encouraged to walk shortly after surgery, and then three months out, doctors cleared her to run again. She picked up steam from there.

“You only live once and I sometimes feel I’m an unstoppable force,” she told Ipswich Star prior to the race. “My dad died when I was little and my mum has always given me a zest for life. I want to make people aware that even if you have major heart surgery you should not be a quitter.”

Even though she didn’t race at all before the London Marathon, she still finished it in 5 hours, 29 minutes, a very respectable time.

“The sense of achievement as I crossed the finish line was immense,” she wrote on Women’s Running UK. “I was the happiest person on the planet. Willpower, stubbornness and determination pulled me through.”

Not only did she cross the finish line, but she raised almost $3,500 for Heart Research UK to support the medical research put into preventing, treating and curing heart disease. The organization also funds community-based lifestyle programs.

Since that milestone in 2014, Borghesani has run three more full marathons, even achieving a personal record of 4 hours and 39 minutes.

How’s that for heart?