I agree totally about not measuring your heart rate if you are someone who is already nervous and worried about your heart rate.. I will just make it worse. A couple years ago I developed this weird obsession with my heart and just about everyday I convinced myself I am going to have a heart attack and anyways I used one of those heart monitor apps that you put your finger on the camera and I would check my heart like every fucking hour of everyday for months like a fuckin weirdo... anyways long story short after going to the Dr (multiple times) and her telling me there is nothing wrong with my heart and the chances of me having a heart attack at this age are pretty slim I FINALLY got over the obsession and I deleted the app from my phone... Tbh I still get feelings like "I'm like going to have a heart attack" kinda often but when I do I just tell myself "you're not having a heart attack" and immediatly put it out of my mind and continue doing whatever it is I'm doing and within a little while I feel back to normal again.. if you worry it will just make it worse because your body will release adrenaline and other panic chemicals and hormones.