Discipline—a skill that can be developed.  But why would you want to?  There is a fine line between discipline and
drudgery.  What do you get for your
dedication (for that is what discipline is)? 
Are there rewards?  Is there a
goal you wish to achieve that has been eluding you?  What is holding you back from accomplishing
it?  Is it the lack of discipline, the
lack of desire, the lack of devotion, or merely the decision to go for it?

You may tell yourself you lack
the discipline to reach your goal, but truly discipline is a choice and one you
must weigh.  The choice is up to you.