Turn the autolock off when you go outside, keep the phone unlocked. You can turn it back on when you're done, it's a single prefs switch. And change your lock screen image to 'REMAIN INDOORS'.
You're thinking of something else. I mean specifically 'auto lock', the thing where the phone locks by itself after a timeout. It does not require turning off pay, changing PINs, passwords, etc. You just have to keep your phone unlocked while you're out.
