PRs: 5K 14:53, 10K XC: 30:29 all from college.
Nothing fancy compared to people I trained with.
I've read Once a Runner a long time ago. Training life is similar - it's all consuming really. In many ways it's like a job and a way of life.
Since I gave up running and got on with my life, I still train and compete competitively - even low key competition is enough to keep things interesting and motivating even though it's not the way of life it used to be.
I don't recommend that people do marathons actually. I've done 3 and they take such a tremendous effort to recover from that a lot of people just stay on the couch and don't start running again.