ENGLEWOOD, Colo. -- Bob Alexander is not afraid of challenging his body.

For more than 30 years he has been competing in endurance activities from marathons to 100-mile bike rides. He even completed an Ironman Triathlon in 2003.

"It's my hobby. I just like it, " said Alexander while relaxing before starting another training bike ride for the upcoming Triple Bypass, a 120 mile bike journey over three of the Rocky Mountain's tallest peaks.

What's surprising is that just six months ago, Alexander underwent open-heart surgery at the Cleveland Clinic in Ohio.

"There were signs, a lot of signs. I ignored them," said 55-year-old Alexander.

Because he thought he was in ideal health, Alexander admits he never even considered that his heart was failing and causing vague symptoms like fatigue, shortness of breath and anxiety.

"I just thought, 'I'm getting older' or 'it must be the altitude,'" said Alexander.

Far from it.

Alexander credits his wife, Karen, for the discovery that ultimately saved his life and possibly that of his son.

"She kept asking me to get a routine physical. I made every excuse in the book like a typical guy," said Alexander.

But, he finally went.

"My doctor listened to my chest. Then, he stopped and looked me in the eyes and said, 'Bob, I hear a heart murmur'. I was shocked," said Alexander.

Further tests revealed a genetic heart defect that had previously been undetected. Alexander had a severe mitral valve prolapse and a dangerous arrhythmia called a polymorphic ventricular tachycardia.

"Forty percent of my blood was leaking backwards instead of going forwards and pumping to my muscles. It was completely rare," said Alexander.

During a stress echocardiogram, Alexander's heart failed and he almost died. "I saw my heart rate jumping around. It went to 225 then to 128. I started to black out. Doctors told me I would need open-heart surgery as soon as possible," said Alexander.

That surgery was scheduled in late December of 2009. Alexander hoped it would repair his damaged heart valve and give him the chance to complete three of his life's wishes. One brought tears to his eyes while talking about it.

"I want to be there to walk my daughter Tiffany down the aisle when she gets married. I'm going to have that chance now," said Alexander.

He's now six months past the surgery day and recovering faster and stronger than he ever expected.

All three of his children have been tested to determine if they also have the genetic heart defect.

His cycling partner and 23-year-old son, Tyler, does have the same heart valve defect. He's optimistic his condition is less severe than his father's. "I'm glad I know it. I will continue to monitor it throughout my life," said Tyler Alexander while preparing for a bike ride with his father. One thing he always wears is a heart monitor.

In the Alexander family case, simply knowing about their own health has already made the difference between life and death. They hope the experiences they've shared over the past year will also change Tyler's health future.

"It saved his life, definitely. It's just so lucky. It just changes everything," said Bob Alexander.

You can read more about Alexander's personal journey at his blog site, Run For Your Heart.