My girl is a former D1 soccer player. Still plays at a pretty decent level. A few years away from 40. A slow 6k for her is 30 minutes on the treadmill. She got me into running and after 8 months or so I can run beyond 10k without stopping, I might slow down halfway through to catch my second wind but…once you develop that stamina you can pretty much go forever.
When I started running I was struggling to get to 3k. Just gotta be consistent and you’ll get there. And once you hit 5k then you start pushing yourself and run at your top pace until tired (which will be about halfway in) and then slow it down to finish out. Either way, just stick with it and you’ll develop the stamina.
Like breh above said, getting into running is the best decision I’ve ever made.