when you say pain... do you actually mean pain as in something particular is hurting, or do you mean exhaustion/tiredness/heaviness in your legs?
If it's the first example then you need to address that problem and find what's causing it.
If it's the second example, then that's fine... when you get to that stage in your run where you want to stop look ahead and find a marker...could be a lamppost, a tree, anything and tell yourself you're going to keep running until you get to that marker, then have a little break.
Each time you do this try and make the marker just a little bit further away.
Before you know it you'll be running further easier, and not needing to stop
