Live on the edge (of something, maybe not a cliff or bridge)

I’m telling you right now, I am not a risk-taker.  I am a fraidy cat, a wuss, a straight arrow.  I didn’t drink in high school.  There wasn’t even the contemplation of sneaking out of the house.  No illicit substances (other than upside-down screwdrivers and the like) entered my temple of a body during college.  [...]