For the benefit of other members, I'm going to describe my symptoms when I had my heart attack.
I started a health kick, walking 4 km every night with the dogs.
Walking downhill, no problem.
Walking uphill, got a stitch under my sternum, basically right in the middle of my breast plate, nothing severe, and pain radiating down my left arm and sweating profusely. i.e, the classic symptoms.
This happened about 4 times in a two week period, I would have to sit down to catch my breathe. I had no idea that this was an angina attack, where one or more arteries are blocked and restricting the amount of oxygen getting to my heart.
I was working at Forensic Science SA as a contractor and went for a walk to get my lunch, same symptoms as above while I was walking up the stairs. Got back to the office and my work colleague, who writes software for cardiologists, recognized the symptoms and next thing I knew I was being driven to the Royal Adelaide Hospital, admitted and lying in a gurney hooked up to an ECG machine before I could bat my eyelids.
My best advise for those looking to improve their health, is get a cholesterol check before you start strenuous exercise, if like me, you've been a bit of a lounge lizard for far too long.