Eyes Of The Winner — photo by @manoldonchev, founder of PhotoAnthill.
Running a marathon at winning speed takes tolls. It is something extreme to the organism so one should adapt to such stress. And be able to bear it. Something you should not try unprepared. The drain of your body's natural supplies is rea. But prepare and do it, that's fine! I'll be happy to see you through my looking-glass.
M.