Everything I’ve heard, from people with much more experience than I, points towards the notion that running should not be your only modality of exercise.
Particularly, running only one style, such as medium or long distance.
You may have heard this idea already.
My question to those who still only run, and have read this, is: “Why?”
There’s got to be something about running that drives you to run.
Figure that out, and, probably, you’ll be able to run a bit more freely.