Riding high on a wave of successful business ventures, Keith Cunningham decided to personally guarantee debts worth over $100m connected to his real estate business. When the market went south he found himself footing this colossal bill.

"I had a guy in Ireland a few years ago interview me - he asked me the question, 'How does it feel to lose $100m?' I can tell you - it feels really, really bad," Mr Cunningham said, speaking to Newstalk's Down to Business.

Bottoming out...

He reflects that it can be easy to lose your way after you've tasted some business success:

"As we all know it’s really easy to become arrogant and overly self-confident when you’re sitting in a boat and the tide is rising. When the wind is at your back and the sun is in your face it’s really easy to say - ‘Man, I’m pretty good at this.’ Unfortunately, I learned some very difficult lessons the hard way as a result of not paying attention to a broader picture," he told Bobby Kerr.

Keith Cunningham / Nordic Business Forum

Looking back he says, "The tide went out on me and I had guaranteed a tremendous amount of debt."

After a brief period of feeling depressed - he set about learning from his blunder.

He says that it felt like half time in a basketball game, and he was heading of the court trailing by 87-3 as he took time out to reflect on where he had gone wrong.

The Texan grew a pony tail, got his ear pierce, and read obsessively about philosophy and theology, until he felt that he had consumed "all of the ologies."

Coming back

He offered his conclusion to Bobby: "The reality is none of us are going to win the game. It’s not about winning or losing, it’s about how you play the second half. Are you going to play the second half for significance - or are you going to play the second half for fulfillment?"

The businessman developed a new life philosophy - chasing four pillars:

• Pleasure - Exciting your senses

• Happiness - Being grateful for what you have

• Success - Getting what you want

• Fulfillment - Giving what you have

Mr Cunningham says that we need to pursue "all four." Since then he's stuck to the mantra, "Hell on earth would be to meet the man you could have been."

He went on to re-build after declaring bankruptcy and found success in business and as a writer and motivational speaker.

The Texan likens the experience to taking a $100m college course to learn about both himself and the world of business.

Hear his interview in full here:

Keith Cunningham will address the Pendulum Summit this week in Dublin.