Lady Tigers in the Concrete Jungle: How Softball and Sisterhood Saved Lives in the South Bronx.
Now, is is not a motivation or mental toughness book, but it is a great read. I wouldn't recommend it to younger players, at least 16U or mature 14U player. Lot of foul language and rough situations, but I had my DD read it to give her some perspective on how things aren't easy for everyone.
Thanks for mentioning this one, I've never heard of it. It looks interesting and it's only $2.63 on Amazon right now. DD is 2nd year 14u so I figured I'll read it myself first. Thanks for the heads up on the language and rough situations.