Quite a few... but the best one was "Grit" by Angela Duckworth. It could be categorized as a self help book since it deals with personal growth and persistence

Quite a few... but the best one was "Grit" by Angela Duckworth. It could be categorized as a self help book since it deals with personal growth and persistence - but from the point of view highly regarded researcher in psychology. I highly recommend this book since it's good on so many levels. Unlike quackery books into self improvement, her book describes her research and journey into human achievement using the scientific method.