Even when I was in good shape I hated to run. Carrying a pack all day was easier than running a couple of miles. Had to do it so I found intervals were helpful.
Walk 3 minutes, jog 30 seconds, run 10 seconds. Walk 2.5 minutes, jog 45 seconds, run 20 seconds.
Work till its all run and you should be fine. At that point 2-3 miles was just putting one foot in front of the other.
The second thing that helped the boredum was an Ipod. Keeps my little mind distracted. I row now for 40 minutes and it just flies by. Did I say how much I hate running?

Last thing is when did you have a stress test? Make sure things are working alright before you tax them to hard.