My husband (now 81) had a triple heart by-pass 14 years ago (in France at Poitiers). He is absolutely fine. We walk the dog daily and he gardens and does all the normal DIY things, including more heavy lifting than I can manage. He does get cold very quickly and then takes some warming-up - but this could simply be age.
Every other year his check-up includes a 'stress-test' when he has to bicycle like mad (static) and 2 years ago his blood-pressure dropped alarmingly whilst doing this. The resulting hospital stay of 2 days was to shove a camera up through the femoral artery. This showed that one of the by-passes was only working at 50%. It was decided to carry on as we are and he's fine. If he does too much fast walking too soon after a meal he gets angina pains for a minute or 2, we stop and they go.
He had had angina for a couple of years in UK and been told it was OK, b ut when he moved here his GP checked everything, didn't like it and sent him to specialist. I think he would have been an invalid or dead if he hadn't moved.