I built up to that over four to fivish years. I did not do a couch-to5k in one month or anything. I do not feel like its bragging... I know at least three marathon runners and my schedule looks like I do not run compared to them.

I also have done a lot of reading, as a lot of my friends tell me running is bad for your knees. As far as my reading of data goes, there is practically no amount of "bad running"... unless your body says "stop" and you keep going.