I would have to say it has been a while for me. When Joseph got home from his second day of school and Mom& Dad asked him how his day was, we got the typical response "Good." Then, I told Joseph that the Lego he ordered came in the mail. All of a sudden, it was "The best day of my entire life!". His elation was genuine and spontaneous.
Those are the little things in life that make for the best days of my life!
What would it take for you to say that it was the "BEST day of your life" with genuine enthusiasm. What is your 'lego'? Even better, what would it take for us to wake up every morning and say "This is GOING to be the BEST day of my life!"
Or, are our expectations so out of whack that it would take a small miracle rather than making someone else smile, having someone tell you 'thank you' or 'I appreciate you'.
Better yet, why don't you make it someone else's BEST day of their life by doing one of the things above. Give 'em a Lego Separatist Spider Droid!!