I'm not claiming to do better: my "give a motivational speech when I see you in clinic twice a year" approach certainly isn't worth shit.
But just because one approach is important does not mean others are snake oil. CF has a clear biological basis, and there are randomized, controlled trials proving that secretion management (e.g. DNase), glucose control, timely antibiotics and anti-inflammatory meds, and chest physiotherapy work. These trials also establish an average effect size (whereas your anecdote only tells me about you; I have also had patients who took similar measures but still died young). The average person with CF died at age 25 in 1986 -- today it's above 40.