[ksaj]

Donald Trump is one who also believes this. Apparently he believes you only have so many heartbeats, and so you should avoid increasing your pulse.

[bluGill]

People who exercise regularly have a lower resting heart rate. You can likely remove 10,000 heartbeats per day just by doing 20 minutes of exerciser per day.

I don't believe the limited heartbeats theory, but it does support the idea of exercise.