We know what physical fitness looks like & what it takes to achieve it. Spiritual fitness is a bit tougher to define, but it's actually not so tough to achieve. Like its physical counterpart, it just requires some willingness & a little coaching. The latter is what 'The Soul Workout' provides.
The Soul Workout
Central Recovery Press
Mind, body, spirit: thought & practice
Getting and Staying Spiritually Fit
Mind, Body & Spirit