I am now retired and worked at a desk all my life, bad posture not enough exercise. Spent a fortune at the Chiropractor, where I would endure the pain [of the treatment] and get relief for a few weeks - than back to the excrutiating neck pain.
Eventually went to a Sports Physiotherapist who was slightly to the right of Attila the Hun - "you have bad posture - SIT UP STRAIGHT" normal greeting. Anyway, she lent me this book.
Bad move. The exercises worked, I bought my own copy and never went back to her! [She's a lovely lady, really - as she sorted me out.
If you have neck pain. Get the book. Do the exercises how and when instructed; [sometimes every two hours] and the pain will go, well mine did :-)