Vero nails what I’ve thought for a long time:
Since I moved from Canada, I have seen too many Brits or Europeans be very sheepish about self-promotion. American sales people are reputed to be bubbly, brash and bigger than life, speaking louder than anyone else in the room and gesticulating endlessly to illustrate what they’re saying. Quite at the other extreme, British marketing folks are often seen to be more reserved and self-deprecating.
It’s worth reading the whole post; particularly her tips for breaking the habit. I’ve been to some Toastmasters meetings, but I just might give karaoke a go.