To offer a contrary opinion, not everyone is cut out to be a pilot.
If you cannot self motivate, maybe your unconscious is sending you a message?
Coming off the runway is frightening, I very nearly did it once when a brake stuck on landing and my heart rate must have been 180 or more afterwards.
The question is has it affected your confidence (understandable) or is there an inner message that it was an accident waiting to happen. You have taken lessons over an extended period, so this has not helped - all of us prefer recency in flying, it makes it easier for us.
Have you discussed this with your instructor and got some straight feedback about your flying ability?
If s/he tells you that you are safe and were unlucky, that is one thing, if you get feedback saying your are marginal ability, that is another.
Good luck, however you choose to proceed. Being a pilot has a strong element of decision making, so think it through, look at your options and then make a positive decision.
Last edited by Final 3 Greens; 23rd Mar 2012 at 11:29.