I would like to suggest three books I read to get me motivated. Also I have tried many apps but I settled with Zero and purchased premium for the coaching videos aspects which I find useful as daily reminders. If you search any of these authors on Spotify, there are interviews and podcasts by each.
The books are:
The Obesity Code by Jason Fung
The Complete Guide to Fasting By Jason Fung and Jimmy Moore (Available as an audiobook).
Delay, Don’t Deny - Living an Intermittent Fasting Lifestyle by Gin Stephens
I go back to these books often to help with various aspects of fasting and hunger.
Hope this helps, all the best.