After being an idiot and keeping all of my savings in cash (well, savings account) for way too long, I basically did a lump sum dump into investments.
In late September.
I've lost 10% of my life savings in the last six weeks thanks to this market slide. Yes, I know I'll get it back at some point. But I can't help but think "what if I'd just waited two more months". Even if it still slides, I would have lost so much less. FML.