two marathons in two months?

[Deleted User]

I ran the Sri Chinmoy on Sunday in 3.05 - my first marathon. I intended to use it as a training run and to drop out after 20 miles but felt pretty good so continued to the end. I'm now asking myself if I've peaked too soon and have ruined my chances of a good performance in NYC on 3 November - any suggestions about how to structure my training between now and then?