Hi - great question, the marathon is 75% mental 25% Phyical
I break London up in to 4 quarters
Start to Cutty Sark - my settling in quarter
Cutty Sark to Tower Bridge - settlled in and looking to get to half way, undercook rather than overcook,
Tower Bridge to Canerie warf - this is the dead zone, this is were you have to concentrate, you are going away from the finsh, and the crowed are pritty quite
Tower Bridge to Finish, feeling tried but on home straight, croweds will pull you though
Good Luck