I took up running 18 months or so and have gone from not being able to run more than a mile without stopping (despite being relatively fit from football and cycling) to being able to run 10km in just over 50 minutes relatively comfortably.
What I found was I needed a route that wasn’t too long and to take it steady (force myself not to start too fast) and be able to finish it without stoppping. Then I kept doing that regularly and only very gradually upping the distance (fortunately I can run out along a river through a park and woods and there are opportunities to cross the river and come back the other way at fairly regular points).
At first I found it was a psychological barrier that I had to break (knowing that I can run a certain distance without stopping). Later, having broken that, I found that I had a problem with shin splints and pain in the ankles and feet after I upped the distance, but after perservering (and not overdoing it) that went away too.
I’m now at a point where I have a speed that I can feel like I can run all day at (not that I’m going to) and another that I can push on at and do a reasonable pace for my current regular run – or do a slightly shorter one a bit faster every now and then.
Also I did find that buying some proper shoes helped – partly they definitely felt better, but also spending money on new gear is a good excuse / motivation to get out and do it when you might not otherwise.
Oh and the other thing is I made it part of my routine – I get up and run every saturday morning before doing anything else, so I’m out doing it before I get chance to think about whether I should or not and find a reason not to.
hth