I got bored with half marathons and was not sure of my best distance. The marathon was the next distance and the only one I had not tried.
My first was run cautiously and I finished feeling pleased but sure that I could do better. I ended up doing the same UK marathon five times improving mostly. Did Manchester the year before the Commonwealth Games. Got bored again. I found that I qualified for New York so off I went. Loved NY so did it twice, actually went three times but was injured one year so did not run. I have since run Paris and Berlin a few times and went to Boston this year but deferred to 2013 because of the inordinate heat (33C)
My marathon times have plateaued to some extent. I am now chasing the experience rather than a new PB but may challenge my best time again. At most I only do two marathons a year so that I can run them well. I still do shorter distances and now enjoy them more.
Unlike shorter distances the marathon has not 'bored' me. It is such a long way and the training takes so much time that you must be focused to finish it with a sense of achievement. I love running 20 miles early on a Sunday morning through country.
However I have found that running any distance is like any other training in life. You must take it a little bit at a time, build up experience gradually(distance and speed), learn about your equipment, learn from your mistakes and realise and accept that your ability may not be in proportion to the effort you expend. What you learn from running can be adapted to meet most things life throws at you.
Mar (marathon) 10K (tenkay) = Martenkay