I have been running for twenty years and completed several marathons, this is how I started training. First and most importantly is to have good running shoes. Go to a running store that specializes in running so you can be fitted properly. I would up my miles by 10% every two weeks. With having one hill training and speed training in my weekly training sessions. After the fourth week I would lower my mileage to about 60% for that one week for rest, then pick back up at the fourth week mileage to build the next four weeks. Now what did I do for strengthening, I would focus on running form, imagine a broom stick lined up against my back. This would help me pace better. Lower body weight program would be for me, I would be lower on weights with higher weights twice a week. I would also focus on core, lower back and a lot on my upper back and shoulders twice a week. I did do a little on chest and arms, but not as much as the others. My experience is that when my back and shoulders where strong it help my arm swing more comfortably after running for over three hours. Hope this helps:) Good Luck with your running!