thanks for the reply guys
Donutz, perhaps you're right, maybe I'm trying too hard, but it seems like that's the only way to control the board.
Poutanen, I was also thinking that the boot fit might be a factor in making my foot tired. When I flex my toes, there is some room in the boot and my heel slips a bit. So maybe I'm using extra foot muscle power because some of my muscle power is spent flexing my toes, but that energy is not translated to the board/binding because it's used to just flex my foot out of the extra space in the boot. Therefore, I must flex more and perhaps harder, because my first flex muscle usage is spent on slipping/extra space, so I must flex even further or harder to have that energy be translated to the board.
Does this theory sound ok? And do you have any more suggestions as to what I'm doing wrong? Thanks.