Sorry, You did mention your age 15!
You didn;t mention your age not that it really matters. I'm almost 67 and my resting heart rate is about 60-62. If you're healthy and not on any meds.
it's OK. Your resting HR should be taken First thing in the morning before you get out of bed! have a clock with a second hand and check your resting heart rate for 15 seconds then multiply by 4.
Lol I meant resting sorry.