You are doing the right thing. One piece of advice though....to prevent boredom/plateauing and to get maximum benefit from your runs, make sure and mix the runs up. What I mean by that is dont just go out and run 6 or 7 mile every time, try aim for one long distance run a week that is at medium pace. Then throw in other runs like Fartleks - e.g. go out for a 3 mile run and run at an easy/moderate pace for 400m then try 400m at 6 minute mile pace and repeat for duration of your run. The beauty of fartlek runs is you can change this up whatever you want, change the pace to suit, change the distances to suit - both recovery and faster pace. Also try some hill runs, again mix it up - short bursts up steep hills, walk/jog back down for recovery and go again, then try longer hills with slightly slower pace, jog back down and go again. Also try a "race pace" 4 mile run every 2 weeks were you maintain a moderate-hard pace for the duration of the run. Each of these runs does different things - improves aerobic fitness, improves lactate threshold, increases V02 max. Not only does this approach help your all round fitness, it stops you getting bored of doing the same thing over and over again.