Spiritual stamina comes from whatever you can have persuaded in this life time as in speaking of matters of the spiritual stuff. There is a stamina to everything, and the spiritual stamina is about being free in mind to choose, the highest possible outcome everyday.
Being spiritual is also something happening for yourself and for being better off with your pride on yours shoulders. You can rebuild the stuff you have in hands, but you can also come back to being precious and stable. Follow your intuition and develop this stamina.
Stamina comes down to this: it’s about having patience, and being able to be bravery and boldness on its own. Be brave, be bold, be shining.