In-Universe, no real canon answer I know of, but he was a man living in fairly poor conditions (backwater crap of a planet, with really poor infrastructure, and he lived in a cave in a boonies to boot), who had major psychological blows (Leaving aside any war-related PTSD, he raised the damned Darth Vader! And everything he ever held dear was destroyed, along with most of his friends).

Oh, and he has responsibility to watch over the pretty much only hope of the Galaxy, and s fully stymied in raising him properly due to Owen Lars' intransigence.

In-Universe, no real canon answer I know of, but he was a man living in fairly poor conditions (backwater crap of a planet, with really poor infrastructure, and he lived in a cave in a boonies to boot), who had major psychological blows (Leaving aside any war-related PTSD, he raised the damned Darth Vader! And everything he ever held dear was destroyed, along with most of his friends).

Oh, and he has responsibility to watch over the pretty much only hope of the Galaxy, and is fully stymied in raising him properly due to Owen Lars' intransigence.