Will I ever run a real Marathon?

I've been very quietly wondering if I will or can ever run a real marathon? 
The 10km that I did and will be doing again..are not Marathons.  Anything below 21km are considered as RUNS ..only.

10km vs. 21 km...it's only two times the effort ..ma. 
Instead of 1.5 hours..it will be 3 hours...o n l y...
Instead of having one and another quarter ankles being sore and limping for half the next day...may be both ankles and both knees and both calves will be crippled for the whole of the next day ..o n l y.


Surely..I can do it......r i g h t?


Now..after reading THIS ..an entry from another 10km runner who tried her first Marathon at the Penang Bridge......



I am is serious Doubts.