Lost Diary is a diary entry that can be collected in Metro Exodus.
Location[]
The Taiga: Back on the road, walk down it until you run into a herd of reindeer. From there, walk towards the riverbank until you find a fishing shack. The diary will be on the crate right in front as you enter. This is also where you encounter a non-hostile pioneer.
Transcript[]
I can't take this anymore... I just can't. I'd be better off alone! I can manage. I can fish, I can go mushroom-hunting... I thought one shot would be enough... I didn't kill him! I just closed my eyes and squeezed the trigger... Everybody did the same anyways! But I just can't do this anymore. And they keep insisting! Calling me a coward! But I just can't kill, I'm not a murderer....