Sanity's but a finite resource in life, and you've only got so much to spare until you're finally out. I can't say I've been around nearly as long as anyone who would call themselves "old", but I think the amount of time I have in this world relative to my mental state is such where "old" is an appropriate label for me.
If there's one thing I could change in my life, I would've been more sexually active rather than just saving the sharing of beds for "once every 10 paychecks". Sure, I probably wouldn't have nearly as much cash in my savings, but I sure as h### would have less of an attitude problem that led to my getting laid off and subsequent visits to a maddening employment preparation program that I'll eventually go insane from visiting. Unfortunately, my fate is sealed, and I've only got a week to get my last rites sorted out. I should probably put my last will and testament at a spot on my desk that's easy to notice.