By Tanner Garrity While talking to a friend the other day, I started a sentence with the words “As an endurance athlete …” then promptly winced, caught myself and started over. I was trying to make a point on why I had a lower resting heart rate than the average adult, but my explanation sounded bombastic. After all, I’m not an endurance athlete. I’m just a writer who makes lots of time to run. There’s a reason we chuckle at adults who take their triathlons, CrossFit competitions and intramural sports way too seriously. The time to be an “athlete” has passed. That was high school, and maybe co…