When is it time to stop treating a prolonged low mood naturally?

I’m curious about the collective’s thoughts on this.
Taking someone who has a history of depression, but doesn’t necessarily believe medication is beneficial. They do all they can to boost their serotonin levels naturally, i.e. daily exercise, meditation, nutritious diet, therapy, etc.
I’m sure whether it is a case of depression, or a low period that will soon pass.
It doesn’t stop the person from getting on with life in any way, but everything feels like a struggle.
How long would you wait before questioning talking to someone about medication?