Opportunity knocks only once. You never know if you'll get another opportunity.
Sentiment: NEGATIVE
The sad truth is that opportunity doesn't knock twice.
Opportunity knocks, but doesn't always answer to its name.
Sometimes opportunity knocks, but most of the time it sneaks up and then quietly steals away.
You never know when you're going to get an opportunity.
You've got to grab every opportunity that comes up.
When you have the opportunity, you strike.
One only dies once, and if one does not die well, a good opportunity is lost and will not present itself again.
If opportunity doesn't knock, build a door.
Opportunities are often things you haven't noticed the first time around.
Opportunity does not knock, it presents itself when you beat down the door.