I know people say, oh you gotta get out of your comfort zone, but i feel like i have never BEEN IN my comfort zone. Something always comes along to interrupt it. Like i dont even want to say, oh i brushed my teeth x days, because that will just jinx it. Become a huge setback that may take me months to recover from.

So - would going on this trip become a huge setback that may take you months to recover from? Or however long? Financially? Mentally? Physically? Why did your sister ask you? Will she be travelling alone otherwise? Will people be hurt if you dont go?

Rereading your post - the last thing you say is that youre not healthy. That would be reason enough for me to just say no.