Nearly everyone has heard the story of the little girl who is engrossed in drawing a picture during class. When her teacher asks what she is drawing she replies "God". When the teacher replies "well, nobody actually knows what God looks like", she replies "they will in a minute".
One of our most fundamental blocks to measuring creativity is our inclination to start three steps into the idea generation process. Before any ideas are recorded, do you find yourself saying "that will NEVER work", and leaving the notion float away with the other inspired debris that occasionally circulates in your mind?
Therein lies yet another problem, what is the solution we come up with is to another problem? Must we be prescriptive in focusing in on one problem at a time? If you decide not to fish that piece of debris out from the water, what chances have you of finding it again? Will you remember the problem or challenge again to remember the solution?
A final barrier as I see is our traditional approach to assessing anything. Our grading system doesn't take account of deviation from standard processes and practices as a good thing. We reward people for regurgitating existing knowledge, not putting forward some new stuff. And, can those who are in the position of awarding marks spot creative potential? As it stands there is no creative grade within our education system in Ireland. The gateway between second and third level is shut, and the password for the time being remains: "Leaving Cert Examination".
We like to quantify our efforts, and ensure our time isn't wasted on something, which is reasonable. Creativity however, does not always play by conventional rules. If you really want to grow your creative capacity you could try one of the following:
Collect notions/ideas without judgement, and review after a few days or a week. Force yourself to overcome the inner critic which will balk at some of your ideas.
Spend some time actually being creative. What you do with that time is up to you, so long as you see it as creative time.
Meet people who ask you stimulating questions. They don't have to be in the same field as you, they merely have to be interested in what you are talking about. Sometimes acquaintances can be better questioners than friends, unless you are looking at forming a hive for idea generation.
Review old "creations". Tapes of music you composed, artwork, scribbled poetry. All of this is unique to you. I guarantee you will see something in what you created before. The joy is that it still in there somewhere.
Finally, and this is most important, stop telling yourself you are not creative. Creativity isn't an exclusive club for artists. It is everyone's right and ability to express something. We are all creative to some extent. We may have just have unlearned it along the way.