Fear is Fear itself...yeah right!

Well I don't know about anyone elses kid but Lexi has absolutely no fear of things...(Except strange men) She will walk right off the edge of anything and everything. She runs away from me at the park or wherever she is down to roam. On our vacation I let her fall off the dock to see if that would put a little fear into her but oh no that didn't work either. So does anyone have any solutions for me or is this just a phase? I mean I am glad she isn't afraid of every little thing but it would be nice if somethings scared her a little so she would be a little more cautious. Please Help me!