For many first time marathon runners, finishing the race is the only goal. No matter how tired you finish, no matter how long it takes, only one thing matters : running (or walking) past the finish line.
Once this goal is reached, the next one, most of the time is to run a faster marathon. But how can it be done? What training should be chosen? Is interval training too difficult for runners with little experience?
In this interview in the NY Times, Running coach Greg McMillan answer this simple questions. A recommended reading.