Are you optimist or pessimist?

Do you think you are optimist?
My answer is ''No''.I don't believe I am an optimist.
But most of my friends say I am an obsolute optimist.

In Philippine,I met a lot of Korean friends.
One day,I walked along street with my Korean friends after drinking.
Although i didn't notice it, I had gotten my wallet stolen.
I didn't notice it,until I paid for my ice cream.

But I gave up on my wallet as soon as I realized it.
And said to my friends,''OMG,my wallet was stolen.
They looked surprised to see this.They must have thought of like this.
''Why are you smiling in this situation?''
That's how they say I am an optimist.

But I think there is no use regretting past.
I can't change what happened.and I knew that my wallet would never come back.
If we worry about past,nothing would change,but one thing would change.
it's our feeling.If we worry too much about past,our feeling would go down.
Is there anything beneficial?
So that's why I never regret my past.
It's good to learn from past,but not good to regret.
Just let it be,accept it,and put it to good use.