I don't know why. Or when it started. But somewhere along the line, I've become a big girl's blouse.
Let's say that you've just asked me if I want to do a bungee jump. Cue mild sweats, fast thinking ways to avoid the situation, and notes to self never to answer the phone to you again.
Or maybe you've got a really good idea for my hen do - we're going swimming with sharks. (Note to hens - we better not be.) My throat would tighten, a sound night's sleep would be out the window, as would our friendship.
My fear of adrenalin was highlighted this weekend, with a visit to see a girlfriend who is in the RAF and flies fighter jets every day.
This friend, she gets up in the morning, puts on her boiler suit, probably a pair of Aviators, and heads down to the RAF airfield where she pops herself into the cockpit of a killing machine and takes to the skies. One day, she'll go to war.
Now, you might have already painted a picture in your mind of what this friend of mine might be like. Doing one handed press-ups in her own time, eating steak for breakfast. Doing arm wrestles with her co-pilot. Allow me to quash any stereotypes. She has soft, floaty blonde hair. She loves a good pedicure, she wears dresses and drinks white wine. She's planning a wedding, a big white wedding, she has a diamond ring on her finger.
Not exactly Iceman. (Top Gun reference there for the lads.) Yet, Iceman is exactly what she is. A fearless Maverick. While I'm more wouldn't say boo to a Goose. (Top Gun analogy losing its way there lads.)
'What scares you?' I asked her, wondering if spiders and bungee jumps and roller coasters and caves and heights and sharks give her the willies, as they do me.
'I nearly crashed mid air the other day,' she said, off hand. 'That was a bit scary.'
Tough as old boots, this one. And just two generations ago, my own flesh and blood was just as hardcore. Grandma Willis, she flew Spitfires in the war. She was one of the first women to get her RAF wings and paved the way for my friend's career. Meanwhile, her actual descendant, at best, edges towards spiders with a pint glass and a piece of card before running off in the other direction squealing: 'Nevermind, he can move in, we'll move out!'
I never have and never will jump out of a plane. I know people who have. 'I was terrified,' they say. No, you weren't, you can't have been. Not properly terrified, like me, because if you really were terrified, you would have locked yourselves in the loo and refused to come out, (Actually, I'm also afraid of locking myself in the loo. Usually I just prop the door shut with my foot and wee while sort of straddling the space between the door and loo. It makes for a sorry mess but better than running out of oxygen and drinking loo water while awaiting rescue, which is what I presume will happen if I lock the door.)
At best, get me drunk and I'll suddenly turn into Jack Bauer, doing roly polys into hedges and waking up with scratches on my arms. Pretty brave, Jack Bauer. As am I, when I risk life and limb impersonating him. But I'm also drunk. And drunk's no good when you need to fly a plane, or swim with a shark, or get on a roller coaster. Definitely not the last one, you'd sick all over yourself.
When the world ends, people like my RAF friend will be alright. Me? As soon as I run out of contact lenses, I'll be done for. No one is going to care that I can put together a few words in a fancy sentence when they're battling invading alien hoardes and whatnot.
No, it really is time to strap on a pair.
And so, I've taken step one towards ditching the poltroon behaviour. I have just been reconditioned to believe I am not afraid of the ocean. A hippy told me that it was just a childhood fear of a swimming pool cleaning machine (it looked like a shark) and I needed to let go.
Good news - it worked. Just call me Billy Ocean. I have booked in a windsurfing lesson on my upcoming honeymoon, in a bay that used to be called Shark Bay, until they decided it was putting off the tourists and renamed it Kite Bay. And who would be afraid of getting eaten by sharks in Kite Bay? Not I.
(I found a picture of a shark kite. How fitting. I'm even a little bit afraid of it.)