Occasionally he remembers to take a shower because when he smells bad, he instantly is reminded of the thousands of times they've been into battle, and the smell of the yeerk pool the smell of sweat, of blood, and combat, and that eventually leads to who died, and ultimately comes back to how it's all his fault.
His day to day method of getting by would be to do things that don't force him to confront his actions in the war, actions he'd much rather forget. He'd rather remember the parts of the war where it wasn't bad at all (ie. the many uses of morphing) than recall how those morphs were the very same reason why he had to kill or be killed so many times.
Not to mention, Jake wouldn't care about earthquakes. He could just morph into an insact, wait out the quake, and demorph much later. While morphed, he'd be reminded of the times they all morphed insects, and than realize that Rachel isn't alive any more, and then he'd get all depressed again.
