Sunshine

They have now prove that sun on your skin causes endorphins to be released into your system, and people addicted to sunbathing are (in a way) addicts.
http://www.sciencentral.com/articles/view.php3?article_id=218392323&cat=1_7
Sun also produces vitamin D in your skin, and it has just been found to be very good for you.
http://www.sciencenews.org/articles/20041009/bob8.asp
I spent a long time today pulling weeds. This is the only time of the year I do it. The good plants are not big, so I can get to the weeds. Next week will be too late. The sun had me feeling relaxed, and the weeds were everywhere. I wanted to stop, but there was always one more I needed to get. So I got lots of vitamin D.