Your resting heart rate is the number of times your heart beats per minute while you are at rest, typically when sitting or lying down calmly, and is a measure of how efficiently your heart is working. A normal resting heart rate for adults is between 60 and 100 beats per minute.
Mine has recently raised, for the past decade it has been reliable 48bpm.
I had my 60th birthday in 2024 and even though i exercise daily, its now 51bpm.
There are some very interesting articles about RHR, its a great indicator of general fitness.