There is an interesting book I was listening to on audible.com (I'm sure the book is available at Amazon, etc too) that is called:

Spark, the Revolutionary New Science of Exercise and the Brain

I haven't finished it yet, but it is fascinating so far

As for exercise, we were talking on another post about people finding swimming or light walking, stretching in a pool helpful. No jostling around, low impact. If you're to the point of getting out, it may be something to think about. I went today to swim for ten minutes only and I felt better afterward. Try to find a pool and the hours are the slowest, quietest time of day to go. I can't wait to go back!