Why have you given up shampoo?
I've been told that it's unnecessary for having clean hair and possibly unhealthy. So not using it saves me time and money with basically no effort, and possibly I gain some health benefits (I haven't looked into this, but see the Wikipedia article).
This is the public group instrumental rationality diary for May 1-15.
Thanks to cata for starting the Group Rationality Diary posts, and to commenters for participating!
Next diary: May 16-31
Immediate past diary: April 15-30
Rationality Diaries archive