In reply to Fiend: Hopefully i can answer you clearly here;
Most of my climbing for about 9 months until recently had been indoor bouldering, which i used as strength training, but i've had the strength to easily climb 6a for longer than that, i just haven't psychologically believed i could. This meant that i climbed slowly, worrying about falling off excessively, got pumped quickly and didn't make it up every 6a i tried.
I knew i had the strength to climb 6a easily and that my lack of confidence was holding me back. For the first few 6a's that marked the improvement in my climbing i focused almost purely on exactly how i was going to climb the route, forcefully ignoring any thoughts of fear or doubt. It was hard at first, but each time i though about falling i said to myself, 'stop thinking about falling and climb!'.
Doing this for a few routes saw a change in the way i was climbing, instead of being stop-start, resting lots and hesitating at hard sections it was smoother, faster and more efficient.
As a result i was climbing the 6a's easily, without getting tired at all. This massively increased my confidence.
As i climbed more i found it easier to push any fear and doubt to the back of my mind because i was continually seeing myself at the top of a 6a with ease with this new mentality.
This escalated to the point where i truly believed i could climb any 6a and so far i have not yet been proved wrong ( i will undoubtedly, but sandbags are everywhere and at every grade).
It's not just climbing 6a's that i have become better at, it is climbing on a rope in general. The more i am climbing with more confidence and efficiency the less fear i have because i know any danger zone such as clipping of facing a big fall can be short lived if i just keep moving and not hang around worrying.
I'm happy to answer any more questions, but may not reply as i am going climbing haha!