One question - do you have any heart damage, e.g. from a previous MI? That could be a factor. Otherwise, the advice given here about finding an athletically-inclined doctor is good. Why not ask to have a 24-hour Holter monitor next time you have a strenuous day planned? I had my quad bypass at 59, so your may have a faster recovery time, but it takes longer than you might think to fully recover - it was 18 months before felt totally 'normal' even though I was back at a moderately physically-demanding job in nine weeks. Take it easy. No rush.