I'm starting this thread in hopes that others can share their amazing revelations (however minor/major/or silly). So please let me know what yours are - maybe yours is the next one I'm about to have and you can help me get there!! :)
Last weeks realization went something like this:
There are times my stirrups don't seem even, or one is tight with my leg weight against it and one is ok, but not as 'in control' .. I'm not as heavy in it.
I used to think that it was because of slight un-evenness in the leathers, or how I was positioning my ankles or I don't really know - but I certainly didn't feel I had instant control over the problem.
Then last week I was cantering and I stopped the horse and said to my instructor "I'm sorry, I lost my stirrup. My foot is in it, but I don't have it." It felt like I had to point my toes to feel any weight on it.
And it dawned on me: The only way that is possible is I am clenching w/ my thighs. If I relaxed my upper leg, thereby lengthening my leg down, my foot would be tight against the stirrup. My LEGS are longer than the stirrups - so if I ever feel it's loose - not only is it my fault - but I can very simply correct it by consciously not clenching anywhere and lengthening my leg.
Not clenching/relaxing you upper leg can be hard at first because it's bouncy and if you don't have a good seat yet - you kind of use clenching as a crutch. But the next time I cantered and a stirrup felt a little loose - I thought "relax. Lengthen." and suddenly my foot was again in the stirrup & I had good control over my lower leg.
This realization also helped in my understanding of general balance on a horse. Your weight should be equally distributed in each stirrup.. so if you feel "even" but you weight is heavier in one stirrup - even though it feels good - you likely are slightly off. (This is a working theory - I am not an advanced rider so maybe someone who is can comment on the correctness of this theory!)
I hope this helps someone and I look forward to reading other people's break throughs and hopefully learning from them!