me too. wrote:
I have been wondering the same thing lately. But I have a bit more running experience. Started running after a long hiatus about 6 years ago, but I am 35.
Last spring I ran 2:44 on about 60mpw.
What does it take to go from 2:44 to 2:19?
After extremely modest performances in high school and college, I gradually worked my way down from about 2:40 in my early 20s to under 2:19 in my early thirties, with various training interruptions for injuries and law school along the way. My training mileage in the months before my 2:40 was probably around 60 mpw; my training mileage before breaking 2:19 was often (typically, unless injured) well over 100 mpw. Jumping from 60-70 mpw on one run a day to over 100 mpw on two runs a day made a huge difference that was apparent within six to twelve months. I also did a lot of pool-running with a water-ski jacket (this was over 25 years ago, before running in water became relatively commonplace and a market for "aqua jogging" products developed); that was usually done at a very high level of intensity as a means of compensating for my inability to tolerate much high-intensity running on land.
The odds are probably against you, but anyone who claims to know your potential based on what you've told us is not particularly knowledgeable about marathon training and performance.
By the way, I'm not making any recommendations here about whether this whole enterprise is worth pursuing. That's a very serious matter that each person needs to decide in light of his own circumstances. You only get one shot at life (at least, that's my view), so choose wisely.