Whatever your values and beliefs, we all believe in something and look for guidance in some principles.
It helps to connect your green journey to these principles.
Spirituality is here not to be narrowly understood as religion, but in a broader sense, as relating to spirit and soul, and distinguished from the physical nature.
To illustrate, I orient my own life around such guiding values as honesty, humility, integrity, service, and faith, among others. And when I feel stuck or unmotivated, I often ask myself how I could practice humility or honesty regarding this given situation.