If I read you correctly you made an arithmetic mistake, you should have mulitiplied by 6 not 10. There are 6 10 second intervals in a minute.
If I am correct your HR is 8 x 6 = 48 is rather low, but may not be a problem as you say you have high endurance - strong cardiovascular.
Discuss any concerns you have with your parents, that's a good path to follow when you are 14 years old.
Sorry for the typo! i did multiply by six, and i had 13 bpm in ten seconds
I make typos all the time, mind just working faster than the fingers.
Ok, to the 13 x 6 = 78 bpm, I'd say that in and of itself isn't a big concern. If I read correctly you are able to take on aerobic (running) level activity without having unusual shortness of breath or other limitations relative to your age and peer exercise group.
I don't remember for sure, but I think young people normally have a HR higher than young adults - say those over 20 years old who may be more in the 60-70 range at rest.
Why are you worrying about a HR of 78bpm? Normal range is 60 - 100bpm. You're pretty much smack bang in the middle of the normal range. There's nothing to worry about here.
When I was your age my resting rate was always 80 - 90bpm, and I was very fit.
HR increases also after eating.
How dilated are the pupils? Sometimes my pupils are both large and dilated. It can be as simple as the lighting conditions of the room you are in, to things irritating your eyes. But it's always best to be sure with any of these things so you can know for sure.
Consult a Dr.
Take care : ]