I've been running for a few years now, and I've built up to ~45 mpw. A problem I've had for a long is that pain begins developing on the balls of my feet, where I strike when I run. The pain usually begins around the 4th or 5th mile of my easy run & progressively worsens. It isn't terrible, but it's making my runs uncomfortable & worries me.
It hasn't led to any injuries luckily, but I'm not sure how to counteract this. If I could, I'd be fine with running farther. Any solutions?