Life is like a road, sometimes you reach cross-roads with signs where you get to choose the direction. Other time the road you're on ends in a cliff.
When a cliff is encountered the esiest thing to do is look for alternate routes to the left and right - even backwards - rather than surpassing the mental block of not knowing how far down the cliff in front of you actually is. If you decide to stay on the same road, you must jump off the cliff.
I just did that and found out that this cliff was only 12" deep. Maybe next time I won't be so lucky but that's the nature of the "road" and it's various choices, obstacles and cliffs into the unkown -- you never know how deep or shallow the cliff will be; yet, the fear and anticiption experienced at it's edge is always the same.