"Tim, you said your goal is to become a 2:10guy in 5 years from now. Can I ask how old you are now? When do marathon runners peak, is it like other endurance sports, low-mid thirties?"
Matt- My goal over the next 4 years is to run a ~2:15. I am 36 years old now so that would make me a top masters runners.
There is an article written on this very subject http://runningtimes.com/blog/?p=27 which explains it very well.
The unique thing that I bring in to this is that I have a relatively young athletic age. I'm 36 but I haven't put that many miles on my legs and heart yet. I have yet to figure out what training is going to be the most effective for me. I have the structure- I believe- to run high volume and eventually intensity too. Training for Ironman for 10 years I very rarely did workouts up near my LT, I focused entirely on Maffetone training principles which I believe has set me up very nicely to absorb training and grow in to an ok runner over the next few years. I have already missed my peak for this sport but I still have the choice to exploit 100% of what I now have to work with. If I can do this, I think I will run a 2:15.