I recently read this book on my Kindle. Amy Morin in this book brings a scientific process to the topic of mental strength and asserts that this can be improved with practice and discipline just like physical health.
In a nutshell, the 13 takeaways are:
Don’t Waste Time Feeling Sorry for Yourself
Don’t Give Away Your Power
Don’t Shy Away from Change
Don’t Waste Energy on Things You Can’t Control
Don’t Worry About Pleasing Everyone
Don’t Fear Taking Calculated Risks
Don’t Dwell on the Past
Don’t Make the Same Mistakes Over and Over
Don’t Resent Other People’s Success
Don’t Give Up After the First Failure
Don’t Fear Alone Time
Don’t Feel the World Owes You Anything
Don’t Expect Immediate Results
It is all of 250 pages and can be read over a weekend.