Have you ever wished that you knew what was coming? That you had the bigger picture, the whole story, so that you could plan accordingly?  It's frustrating when you don't know what is ahead.  And how can you make the right decisions if you can't see the way?  On a journey, Satnav helps us with that, but we don't have Satnav for life. 
A conversation with yourself might go something like this: "If I knew whether I was going to get promotion, I could decide whether to buy a newer car." or "Shall I take the job? Will I like it? Will it help me with my career progression?"
If we had the ability to rise, like a helicopter, above it all, and see what was coming, our decisions would be easy, wouldn't they?
But we can't - we can be trapped by the "tyranny of when": when I get the new job, I will be able to buy a new car, or when I have lost weight, I will have confidence.
Alternatively, we can appreciate the now - enjoy what we have, and celebrate the opportunities that we have.