I almost religiously log everything with a IPhone app, "gym buddy". It's easy to then check the preceding three or so workouts and choose the most appropriate exercises for my next workout. Stops me overdoing my 'favourite' exercises and so my workouts are more balanced. Stuff I do is pretty basic, anyway.
Iphone? app? My phone is made by casio and I take my notes on a piece of graph paper.
The spirit that I have seen may be the devil: and the devil hath power to assume a pleasing shape; yea, and perhaps out of my weakness and my melancholy, as he is very potent with such spirits, abuses me to damn me.