Do you ever get the feeling that behind your mild-mannered, 'I wear frameless glasses and am scared of spiders' veneer, there's a secret agent just waiting to break out? Like your whole life is this elaborate front for a mission so devious, so confidential, that even you haven't been briefed on it. Or perhaps you have been briefed on it, but in a Bourne-Beeblebrox  kind of way you've managed to hide it from yourself - so that even you don't know what you know.
Do you ever get the feeling that you're being followed, that deadly ninja assassins are lurking behind every shadow waiting their chance to get at you, that fat-jowled men with missing fingers in black-tinted limousines would pay good money for the smallest scrap of personal information about you? Or that deep within your usually clumsy self are the feline instincts of a Shaolin master, just waiting to break out at the first hint of danger?
I do. So convinced of this am I sometimes (or rather, so convinced of this do I enjoy being) that I will do the following :
a) Upon entering a restaurant, I will always choose a table where I'm facing the door and (preferably) have my back to the wall. That way I can keep an eye on everyone who comes in / goes out.
b) I always remember the exact order of my bookshelves - that way if anyone moves a book and doesn't put it back in exactly the right place I know instantly
c) I have a mirror at the entrance to my room - that way I can half open the door and scan the reflection of the room in the mirror before I enter, just in case there is someone waiting for me - in the easy chair, perhaps, a silencer attached to his gun.
d) If someone offers me drinks from a tray, I will never pick the one right in front of me. It might be poisoned.
e) If I log in to a website from somewhere outside my home and office, I will make it a point to ensure that my log-in does not appear afterwards. Many times this means I will go back to the log-in screen and try logging in with an entirely fictitious name, just so my name gets overwritten. I will always clear the browser history as well.
f) On my more paranoid days, I will leave strands of my hair in specific places on my desk. That way if I come back and find that they have moved, I KNOW that someone has been rifling through my stuff (and no, of course it couldn't be just the wind)
g) If someone is walking close behind me (<10 feet) I will either stop to let him / her pass, or watch his / her shadow on the pavement so that I get that split second of warning if he / she makes any sudden or threatening moves.
h) I never take exactly the same route to office and back. I will always vary it a little, even if this means a little extra walking. That way there's less chance of someone lying in wait for me when I go back.
i) I rarely, if ever, allow myself to be photographed. And then only by people whom I trust
j) I have two very different handwritings. I use them intermittently to throw people off guard.
k) I will actively spread disinformation about myself - if I'm going grocery shopping, I'll say I'm going to the library. If I'm going the library I'll say I'm going grocery shopping. No reason. Just so people don't know where I'm going.
 The idea for this comes from a post by DoZ
 I know, I know. I hated the comparison too.
 No, seriously. Scary as it may sound, all of this stuff is true, though a little exaggerated in parts.