Thinking - a hinderance from trying things..??

Conscience does make cowards of us all,
And thus the native hue of resolution,
Is sicklied over with the pale cast of thought,
And enterprises of great pitch and moment,
With this regard their currents turn awry And lose the name of action.

I read this passage in a beautiful article..I don't remember when...but it struck me suddenly and well..the thought process over this made me feel that this is actually true and fits in perfectly for a few perspectives in life..But for others...:-?