The book title should appear on the cover in this order from top to bottom of the cover
One Size Does NOT Fit All
Your Personal Prescription to Manage Stress Naturally
The words "One Size Does NOT Fit All" should take up around 50% of the cover (the top half), and some attention or design should emphasize "NOT"
For "Stress Management" have it be in either cursive or italicized at a slight angle offset from the other words (maybe 20 degrees angled or so, like the word stress starts low and management ends high)
Then use your discretion to integrate the sub-title and author name into the cover design.
The author is: Nikki B. Williams
A book you can reference (but not copy stylistically) are "I Will Teach You to Be Rich" by Ramit Sethi" - Which incorporates the words of the title into the design well.
The topic of the book is stress management in a natural (not medicated) way. So the design should both be bold in it's declarative title, and also soothing or alluding to a stress-free lifestyle as a result of using these tips.