So you always kinda assume that the heroes in a JRPG are stronger at the end than they are at the beginning. I'm talking "in story" here obviously.

Nowhere is this better displayed than with Tidus. Beginning of game Tidus is KO'ed by a single shot from a 15-year-old 50-pound girl. He was also crying about being hungry and cold and needing that fire to survive.

Near the end of the game though he no longer complains about being hungry even though he hasn't eaten since the Al Bhed ship with Rikku. Also he's capable of scaling a snowy mountain all the way to its peak without so much as shivering, let alone complaining about needing a fire.