I'm down to 46 minutes for 4 miles. Personally I think it is great. Only problem is that my freaking ham string has started to hurt. A lot of that has to do with me not stretching properly before and after my little trips. It also has to do with being 6'2" 220lbs running on concrete. Oh yeah and always running the same course every time.
I've fixed the course I take. Basically I still do the same course only now I reverse it for my second lap. That should help undo the issue with always running on the same side. Stretching is also being addressed but I think I need to stretch on the days off too.
The one thing that bugs me is weight loss. You would think doing 8 - 16 miles a week would cause some type of weight loss. I've not really increased my diet. I drink tons of water and other fluids (too much diet coke I'm sure). One thing that frequently comes up with weight loss is that exercise alone will not really cause you to lose weight.
In most ways this is not an issue of weight. I want to be in good enough shape to do things that are physically demanding (racing motorcycles for instance). Getting down to some ideal body weight is not a priority. However, it is still curious that I'm not dropping weight.
The next phase will be to start lifting weights more. I'd like to make it in to the gym twice a week. Ultimately I want to be able to bench press 150% of my body weight, squat 200% bw, do 20 pull ups and 80 situps in 2 minutes. Oh - run 3 miles in less than 24 minutes.
Easy.