stand there, it may take up to an hour, but make him realise that your way is the only way. stand there for say 2 mins, tehn ask him to move forward, if he refuses, stand again, for another two minutes, repeat this process unitl he moves forward. iwould also recommend hacking out with (if you can, and where safe to do so) a horse friend either side, so he's boxed in. it sounds like he is taking advantage of being strong, and boy does he know it! i would recommend a different bit, or schooling him for a while before a hack, so that he doesnt haveenough energy to mess around ,goo dluck! x