Going to echo AJ’s commentary on this. Especially as someone who historically runs too much in Z3/4 (and has an injury history to prove it), I’ve had to work a lot on running in the lower HR zones. I’ve always felt that Z1/2 feel kind of clunky and ungainly, so one of the mental tricks I’ve started using (stolen from Mario Mola) is to think of it as a “trot” rather than a “run”. Also, when I go out for a trot, all I see on my watch is time, HR, and cadence–the only metrics you really need. Running 80% or more of my volume at lower HR has def worked wonders for me, and after a few weeks you definitely get a feel for it.