Imagine you time travel to the future and discover that your endeavor turned out to be a complete fiasco.
Now work backwards from there:
What led to the flop?
What were the possible missteps along the way?
What were the tripping hazards?
What were the warning signs that things were going sideways?
Now time travel back to the present: your prospective hindsight is now foresight.
With what you know now, how would you mitigate potential problems?
This brief pre-mortem exercise isn’t meant to discourage. Rather, it’s an effective way to discover and figure out potential problems before real problems occur.
Lessons learned don’t have to wait for a post-mortem when an endeavor is autopsied. They’re much more useful if they come at the outset and can be applied to improve strategy and execution.