Some of it can be "automated", I guess...

I have a saddlebag on my road bike with a spare tube, patch kit, tire levers and then the pump is attached to the frame. For MTB, I have a camelbak that I prestocked with the MTB's spare tube, some tire levers and a first aid kit. My "commuter" backpack has a pocket that I always keep a lock, a rainfly, pants clips, blinky lights, Action Wipes, and a 10-ride train ticket (just in case!) No thinking or big checklists, just depending on the ride, I grab the appropriate bag.

I have a ziplock baggie with a copy of my ID and my local map. Throw in my cell phone and a few cash bills. My keys have a little detachment so that I don't have to carry the entire ring to get back into the house or car.

I tend to keep my helmet, gloves, and sunglasses together in the same place. No thinking there.

So when it comes time to really go, it's just a matter of grabbing snacks and filling up the waterbottles or bladder.

What I don't skimp on is the pre-ride bike check rituals, or my ABC: Air in the tires, Brakes engaged and functional, and Cleats clean and tight... (tho a recent event triggered me into adding a quick tug on the quick release skewers now, too!)

-- gnat!