Life is far too short and unpredictable to take the half empty outlook. We all go to work in the morning "knowing" that we will go home at the end of the day. This is actual rubbish as we do not know what the day will bring and what we will be doing at the end of it. (from great to bad) You may meet the girl of you dreams at a fuel station or in McD's whils getting your lunch and end up back at hers, or you could have a nasty accident somewhere and end up in hospital or possibly worse.
Grim bit alert...
Nearly 6 years ago I went to work as I do, mon to fri. At 11.00am I was rushed to hospital with 2 of my fingers disconnected to the rest of my body.
In january I went to the doctors with "really bad poo pains" to be told get to a hospital asap as you have an inflamed appendix. It burst while it was being removed.
I think its because of these events that I very rarely, ever get stressed out or moody. Lifes too short, enjoy the good bits, savour the great, forget the bad.