Luke 21. How poor give

Luke 21:3-4 NIV
“Truly I tell you,” he said, “this poor widow has put in more than all the others.  All these people gave their gifts out of their wealth; but she out of her poverty put in all she had to live on.”

until now I still learn how to give like this poor widow.

I remember one of the preaching by someone said this - give until you feel pain.