What doesn’t kill you makes you stronger.
What doesn’t kill you usually makes you weaker. Plus, whimpering is often involved. I learned this the summer I had blood poisoning.

God doesn’t give you more than you can handle.
May I return the gift, please? If this were true there would be no suicides. Not a useful aphorism for atheists, either. And why would people worship a god who, apparently just for sport, will load you up with trouble to the very brink of breakdown?

Everything happens for a reason.
Yes, but often not for a good reason. The fact that cause and effect exists doesn’t mean it’s looking out for us. That’s not its job. 

All of us have a purpose in life.
A good purpose? Remind me again: what’s yours? Did you get it in writing?

When one door closes another one opens.
Maybe, maybe not. Better look carefully if it does.
See “The Lady, or the Tiger?”, Frank Stockton
Also see “No Exit,” Jean-Paul Sartre
Also see “Let’s Make a Deal”

Look for the silver lining.
Sometimes there; often rare. Damn, that sure is a big dark cloud.

It can’t get any worse.
Unless you’re already in extremis, things can always get worse. I learned this from my last house, which disliked me intensely. The leaky roof was compounded by a falling tree branch, which was compounded by a plumbing disaster, which was compounded by two dead chipmunks in the dryer vent, which was….You get the idea. 

When life gives you lemons make lemonade.
Where do I get the sugar?

Think positive.
Think rationally. Also grammatically.

Just try harder.
Sigh.