[LisaS]

I can tell you what I found rehabbing my broken ankle. Your brain/CNS protects you (or thinks it does) - inspite of conscious thought and that takes some time to overcome.
When I first was told to do weight bearing after 6 wks of zero, I was supposed to stand good foot on a book and injured foot on a scale and then shift weight to where XX lbs was on the scale (e.g. 25 lbs or 15% bw, etc). And I would stand there and there was a little pain but nothing to speak of but for the life of me I couldn't shift my weight to that other foot. It was really weird - I was mentally thinking "why won't my weight shift over" and couldn't come up with anything to do to make it happen - obviously this was overcome but it was really striking when it happened. Consciously I had no fear but somewhere the connection was not being allowed at that time.
I'm stil not thrilled about running/sprinting on an uneven surface like grass - but that's getting better over time. I think you just have to re-convince your brain and CNS that the movement is safe outside of rehab for the injury itself.
At least that was my experience.