This book is a treasurehouse of mantras for just about any occasion. Thomas Ashley-Farrand writes insightful and informative books - and I like all of them - and I also enjoy his recordings with mantras.
Together with mantras and their applications, he also provides lot of interesting stories about people who used them and the effects the use of mantras had upon their lives.
Some stories also relate to abuse of mantras, or rather inner power one has developed; while some also point out that it's not only mechanical repetition of mantras that brings desired results, but also investment of one's energy, belief and expectation in their effectiveness [e.g. self-hypnosis].
Mantras do help to focus your mind on a desired outcome, to align you vibrationally with certain frequencies - but you'll also find stories of different people using the same mantra and getting quite different results [the determining factor here being one's belief and expectation].
Together with this book, I do recommend his recordings. All in all, you can sing a good deal of your problems away and align yourself with vibrations of love, health, peace, abundance, happiness, and anything else your heart desires.