1.
S₁: Anything you do that gives you some form of regular exercise will benefit your heart.
S₆: But do not push too hard; tune into the warning signals from your body.

P: In fact, never choose an activity just because it is good for you.
Q: By all means work up a good sweat, and even a thirst perhaps.
R: If you can, combine this with enjoyment, then so much' the better.
S: You will soon get bored of it.