As for aerobics/cardio, I've never really picked up a book myself as I've been hiking my entire life. It really depends on what you're aiming for; if it's just baseline cardio, walks around the neighborhood are good enough. Beyond that you have to specialize a bit depending on what you're aiming for, be it endurance, speed, explosiveness, and also terrain and form. Swimming is probably the lowest impact, but requires a pool. I use cycling for groceries, errands and when I used to commute, but that's sort of an absolute bare minimum. At home I got a VersaClimber clone since I rock climb and mountaineer. I recently got into trail running after reading "Born to Run" but that's less a prescriptive/instructive book than an inspirational/entertaining read.
Recently I've gotten into Yoga as I've been neglecting flexibility. Yoga With Adrienne on YouTube has worked well for me so far.