What about me? I'm not a runner like them. I work out a little bit but I'm not in good shape, I have a lot of bodyfat and my cardio fitness is most likely below average. I'm 35 male and 5'9 and 170lbs, but I have no muscle it's basically all fat. I'm usually at a resting heart rate between 60-65 but recently I've been working out a little more and have lost 15 pounds in the last couple months, and my heart rate has been getting lower and lower over that time. Today I had the exact same numbers as the OP's post. 43 resting heart rate and when I was sleeping it shows it went as low at 38. I definitely don't run 3-7 miles like the OP.. I can barely run down the block before being out of breath. I do light cardio