I have been keeping a log since I got diagnosed and it helps. Before bed I basically just sum up my day and the moods i was in during those activities and also try to grasp the overall mood of my day. It's working quite well. I suggest just a simple phone app for it. I use the stock "notes" app on iphone but there are literally hundreds of free apps the same. Just search "notes" in ur phones shop. Or if u want it on a computer just open up a wors or notepad doc and start logging. It helps i think.