Horror in odd places

Heartbeats are scary. This incessant pump, pump, pump, pump, pump, it happens automatically. You can indirectly influence the speed, make it a little faster, a little slower, but you can't stop it. A part of you moving on its own, out of your control, and if you could ever take control, if it could ever stop, everything stops with it.

Reflex tests are scary. A little hit just below your knee, and your leg kicks. You didn't do that. Did you do that? Your leg did that. Is that you? You didn't choose to do that. But isn't this your body? Is it yours if you can't even control your own limbs?

Laughter is scary. Trying to hold it in makes it even harder. I find something funny, but I don't get to choose how I respond. My body chooses for me. Is it even mine, then, if I don't get to choose? I don't get to react, my body reacts for me. What if I don't find it funny? Why does it laugh anyway? Why do people see laughter, something they know is involuntary, as approval? No, I don't want you to keep doing it. Yes, I know my body laughed. That doesn't mean I want you to keep doing it. But I laughed, obviously I like it. But I don't like it. But I laughed. So you'll keep doing it.

Is this body even mine?

What am I?