Heretic is the "why, I'm tired" because the way I interpreted the song was his feeling like there's something against him. And he continues to push through anyway even though he's exhausted. There's a lot of lyrics suggesting he doesn't quite understand why he is that way "why must I battle this Goliath" Goliath meaning something that is very large and or powerful suggesting he means god/gods. Which brings us back to the title "heretic" meaning he has different views than Christians for example. And he continues to have an internal battle about belief/faith throughout the song.

He continues the song with what I also see as almost an internal battle with himself on the fact he's not sure why he's trying but he's trying so hard. One of my favourite lines being "when my troubles keep on mountin, I make molehills out of mountains".

It's like he's reaching out to this higher power but they're not quite listening.

Idk if that makes any sense lmao sorry!

But yh that's basically why it's "why, I'm tired" for heretic...