Sure I'm Not The Only One Who Does This

Me too!
Sometimes I also try to hold my breath, or at least slow it so it won't look like I'm breathing to see if I can keep up.

I also look at the eyes

I check the carotid artery on their neck to see a pulse

I do it too

I stare at their chest for other reasons
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( ͡ʘ ͜ʖ ͡ʘ)