Some examples:
You have a basket with loose socks -- the mates are lost.
You lost an important phone number or document.
You lost a bet.
You lost a job, a client or a significant business deal.
You lost the ability to do something that you had taken for granted.
You lost a spouse through death or divorce.
You lost a friend through death or disagreement.
You lost a parent or two, or in-laws.
You lost a child.
I can't fathom that last one but I know far too many people who have survived it. They are my heroes.
There were times in the last few years that I was certain I had lost my mind.
