I dont know how strong my opinion holds since I only got 590 on my 1st attempt.
Let me see if I can inspire you .. here goes....
I dont think the GMAT is about intelligence/age/ability at all. Sure, there are some people who are naturally bright, or have a strong academic background, but for the 99% of people, I think the GMAT is something else.
The GMAT to me is a indication of how well I can formulate a strategy and stick to the plan.
The GMAT to me is a personal battle of learning to make sacrifices, applying and disciplining myself and developing a study routine (esp after 10 hr day in the office!)
I believe that these are the reasons behind why b-schools demand a GMAT score.
I've read many posts here, that talked about having attained successful GMAT scores through investing a lot of time, using the right resources, and practicing, practicing, practicing.
I reviewed my last preparation, and in retrospect, when I took my test the first time, I hadn't even covered 1/10th of questions that a lot of 700ers had done.
So, to state the obvious, focus on the areas that you're not confident in, and just train your brain to understand the concepts and then practice practice.
So don't give up hope, chin up, and get back to to it.
ps. If you want to watch something motivational, try the Rocky III .. "Eye of the Tiger"