What causes your adrenaline to kick in?

Fight or flight. During periods or stress or peril our body compensates by releasing adrenaline (norepinephrine) to increase our abilitly to repond to those situations.
Do you want it to? First of all, "adrenaline" isn't a word in the US. You will NEVER hear docs talk about "adrenaline" here. In the US it's called "epinephrine." Second, are you laboring under the misconception that "adrenaline" "kicking in" is pleasurable or exhilarating? It isn't. Epinephrine "kicks in" when you're, say, being held hostage and a gun barrel is pressed against your head. Think about it.