Chances are there's still a chance

What does it mean to take a chance? we always hear the term
"this may be the chance of a lifetime..."- but what exactly does that mean?
what chances should we take and are there some chances that require a second opinion before we leap at them?
and if that is so who gives those second opinions and where can I find them?
maybe i'm just being a silly goose and then again i may be setting myself up to take one of those "chances of a lifetime"
it should be noted that every chance taken, comes with a degree of vulnerability
one that we as feeble humans often never want to arise
you see taking a chance is like playing the game Risk - it involves putting yourslef on the line and more often than not it is the heart that will be placed on that line- a line which may be at times straight, dotted, curved or even invisible to the eye
well.... Mr. I'm not stalking.. this is only hi
i'll take that chance