My heart is almost 22 years "younger"

My resting heart rate was 45 this morning. I was hoping it would be 44, but it didn't quite make it. This is just the second time in 22 years that my resting HR has been below 46. When I ran marathons in the early '80s, my resting HR was 44, and then one day it dropped to 40 and stayed there until I stopped marathon training.