Why do people who start meditating want to sit for extraordinarily long times? If one's mind becomes quiet for even one instant, it would extend itself naturally. Forcing oneself to sit for a long time is stupid.
If you are bored during meditation you are doing it wrong.
Ding Dong, you should perhaps define 'extraordinarily long times'. Is that an hour? 3 hours? 6 hours? 12 hours? 48 hours? I found the exercise of forcing myself to sit for a long time pretty satisfactory. It is sure an exercise of will power related to a worthwhile endeavor, and such exercise can only be good (barring the slight headache which can develop).
