To launch a series on celebrities and their health, the BBC News website talks to British explorer Ranulph Twisleton-Wykeham-Fiennes about his life after a heart attack and bypass operation.
Awarded the OBE for human endeavour
Sir Ranulph, 61, began leading major expeditions in 1970.
He had earlier been dismissed from the elite SAS regiment following a practical joke in which the set of the movie Doctor Doolittle was blown up in Wiltshire.
He then went on to work in the Middle East with the Sultan of Oman's forces, before setting off around the globe.
Described by the Guinness Book of Records as "the world's greatest living explorer", one of his greatest adventures was the 52,000-mile Transglobe Expedition - the first surface journey around the world's polar axis.
In 1993, the Queen awarded Sir Ranulph the OBE for human endeavour and charitable services. He has gone on to develop a career as an author and motivational speaker.
HOW DID YOU FIRST REALISE SOMETHING WAS WRONG?
I had absolutely no indication anything was wrong until I woke up in a hospital bed and was told I'd suffered a heart attack.
Before that there had been no obvious signs - I hadn't experienced any pain and was living my life as normal.
In fact, before my heart attack I had boarded a plane and was reading a magazine. I was later told that I slumped forward without warning.
Luckily one of my fellow passengers was a nurse, and the stewardess was very quick to call the emergency services, which arrived, with a defibrillator, within four minutes.
It took 13 attempts to get my heart beating and I was in intensive care at Bristol Royal Infirmary on a life-support machine for three days.
Looking back, my annual check up with my GP had shown my cholesterol was slightly higher than normal.
We all know high cholesterol is a risk factor for heart disease but at the time there seemed no cause for concern as I was otherwise fit and healthy.
HOW DID YOU GET DIAGNOSED?
When in intensive care, I had an angiogram, which showed where my arteries had become narrow and that I had had a heart attack.
WHAT WAS YOUR REACTION TO THE DIAGNOSIS?
I don't remember how I first felt when I woke up in hospital to be told by my late wife that I'd had a heart attack.
The world's 'Greatest Living Explorer'
My initial reaction was probably one of annoyance because I couldn't remember anything that had happened on the day of my heart attack or two days before.
A further reaction would have been one of disbelief - I hadn't smoked for a long time and was fit as I'd been training to run seven marathons in seven days.
WHAT WAS YOUR TREATMENT?
I remained in hospital for some time after my heart attack and had a double bypass operation.
I now take aspirin, a statin (cholesterol reducing) drug, and a blood pressure lowering drug called an ACE inhibitor, and am very aware of my heart health.
HOW DID YOU FEEL DURING TREATMENT?
Once I had fully recovered from my double bypass operation I felt fine.
I experience the odd bout of angina but feel as good as I did before my heart attack.
I felt good enough to run seven marathons on seven continents in seven days for the British Heart Foundation four months after my operation.
HOW DO YOU FEEL NOW?
Good - I just have to keep my angina under control and I take more of an interest in looking after my heart health.
I made an attempt to climb the Northern ridge of Everest this summer in aid of the British Heart Foundation.
WHAT IS YOUR MESSAGE TO OTHER PEOPLE WITH THE SAME CONDITION?
In the UK we have specialists that do such a great job of treating heart attack victims and helping prevent future heart problems that you can normally get back to doing what you did before.
I ran the marathons and attempted Everest for the British Heart Foundation because, as the nation's heart charity, they're raising money to fund pioneering research into the causes and prevention of heart disease.
I'm president of the Ranulph Fiennes Healthy Hearts Appeal, which is raising funds for vital research equipment which will enable BHF professors to further their pioneering research into heart diseases that affect young people, so it's vitally important enough money is raised.