* "I'm leaving my job because I'm underpaid." = I get it
* "I'm leaving my job because my boss is an ass." = I get it
* "I'm leaving my job for a more prestigious company." = I get it
* "I'm leaving my job because I lost passion and am not learning." = ???
If you want passion, try volunteering or get a hobby. If you want to learn, there are plenty of opportunities to do so outside of work. These are problems that can be solved without jeopardizing your ability to put food on the table.
Introspection is great for its own sake, but to me it's a little weird to mix it all up with your employment. Work is a financial transaction/relationship. You trade your labor for compensation. When did it become something we have to love and wrap up so much of our self-image into?