One of the unexpected upsides of my meltdown and rebirth (aka Sunday of Doom aka Disastrous Day Off) is I realized that if I'm having a hard time writing past the second act, it would be a good thing for me to study how others do it.
Since then, I've watched Bolt, Police Academy, and an episode of Legend of the Seeker. In each, it was actually pretty easy to pick out where the second act ended and what event changed the main character(s) and renewed their urgency in the quest, which then culminated in the third-act climax.
Bolt I thought was going to be the easiest, with Disney and children's movies in general being more obvious about their story arcs, but it was actually Police Academy that was the easiest. I'd probably have more problems dissecting other elements of the spoofy movie, but the acts were very clearly defined.
I've also passed the second act climax in Ten Big Ones, and it was good to see it in written form. Hopefully recognizing second-act climaxes vs. third-act finales will help me imagine more complete stories from the beginning. Only time will tell. At least it will improve my editing.