Reply one: You're right, that is the point. I don't give a toss. But each year I am invited to the "Cardiac Desease Clinic" for my annual check. I know many people who have never had, "Heart Disease" who in a far worse sate of health than me.
Reply two. You ask what it stops me from doing. The simple answer is nothing, so long as it doesn't have life threatening consequences to myself or anyone else. The reason I bring up the issue is that being 75 and having "Heart Desease", based on the Covid 19 rules, I'm supposed to lock myself away, not move out of the house and die quietly. I can assure all of my "Cardiac Deseased" peers that I am at present walking a minimum of five miles each day. This may be flouting the lock down rules but I am sure that walking in isolated countryside for a couple of hours each day is not threatening the wellbeing of anyone. The back and hip ache a bit when I get back home but a couple of paracetamol sorts that out.
My message being, if you're used to getting out and about don't let this current situation tie you to the house. Obviously stay the recommended two metres apart from others. Wash your hands when you get home and enjoy a large G & T.