BSFSH is based on an idea from Jocko Willink's excellent book Discipline Equals Freedom: A Field Manual. In it, amongst the very many other really good ideas he talks about, he speaks to the struggle against our worst enemy, our own lack of will - and how if something does not make you better, stronger, faster or smarter, it is something to be avoided completely.
And thus, BSFSH (Better, Stronger, Faster, Smarter, Holier - my addition) was born.
In a way, it is a very simple rubric. Starting with my activities and my restated goals, I can query each and every one of them:
Will it make me better? Will it make stronger? Will it make me faster? Will it make me smarter? Will it make me holier?
If not, it is something I need to avoid, phase out of my life, or replace.
An example would be weight lifting - it makes me stronger. Or Iai, which makes me better, stronger, faster, and smarter (almost the quinfecta). Whereas something like eating doughnuts every day or choosing to watch things which neither recharge nor educate nor refresh do none of these things.
Try it. Go through your life and ask the questions. The answers might surprise you.