I also have the amazing paranormal ability to "alter my heartbeat", it's called jumping jacks.

It wouldn't have been much of a prank if I was so obvious about it, would it? I did it while the doctor was actively in the process of taking my heart rate by concentrating and taking either shallow or deep breaths as sneakily as I could manage. I was simply wondering about the connection to this type of meditation as meditation is often concentration and breathe based, there's nothing paranormal about it.

Ha, that's interesting. In what way did you alter your heartbeat?

That is to say, I would imagine my heart rate speeding up or slowing down and either take shallow or a deeper breaths at different speeds. I remember that I figured it out once when the doctor commented on how high my heart rate was and I slowed it quickly enough that they actually mentioned it. After that I started doing it as a game, which I eventually got bored of as children do.

I do wonder how effective I actually was, as it isn't really something I have thought about for literal years.