When did Tom realize that he had to be a thoughtful and economic fighter?

Throughout his fight with Sandel, Tom King shows remarkable caution. After the bell rings, he doesn't leap out of his corner like his young opponent, eager and ready to fight. Instead, he advances but a short distance, acutely aware that, without proper training, and without enough food inside him, he has to make sure that every last step counts. Also, King had to walk two miles to get to the boxing ring, so it makes sense to stick to his policy of economy and expend as little energy as possible. Whatever happens, he must maintain his strength at all costs.
Sandel comes at King like a whirlwind, but his older and heavier opponent holds back, angering members of the crowd, who want to known why the old slugger isn't putting up more of a fight. But King knows what he's doing; he's an experienced fighter and sticks to his game plan for the rest of the fight. Sadly, it's not quite enough, and Sandel's youth and energy prevail as he defeats his aging opponent by a knockout. As he commiserates with himself, King feels sure that he would've beaten Sandel, and that his thoughtful, economic strategy would've succeeded, if only he had eaten a nice piece of steak beforehand.