Paul speaks of devotion to the Christian faith as if it were grasping the faith with one's hands. Alternate translation: "be devoted to" or "know well" (See: [[rc://en/ta/man/jit/figs-metaphor]])
The word "healthy" here is a dead metaphor for true, trustworthy, and morally good. Alternate translation: "trustworthy teaching" (See: [[rc://en/ta/man/jit/figs-metaphordead]])