Turbulence is weather, not structure, and it behaves like water

The most useful mental change a nervous passenger can make is to stop picturing air as empty space.

Air is a fluid. It flows over mountains, spills off their far sides, rolls in the heat above sunlit ground, and shears past neighbouring streams moving at different speeds. All of these produce eddies, exactly as a river does around a bridge pylon or a boat crossing the wake of another. When an aircraft passes through those eddies, the local direction of the oncoming air keeps changing slightly, so the amount of lift keeps changing slightly, and the aircraft moves in response. It is a boat on a choppy harbour, not a building in an earthquake, and the difference in mental image is enormous.

That distinction matters because bumps feel structural and are not. The aircraft is not being struck by anything. It is riding a surface that happens to be uneven, and the deflections are far smaller than they feel, because human balance organs are exquisitely sensitive to changes in vertical motion and utterly indifferent to the fact that a wing is being asked for a slightly different amount of work than it was a second before. Loose objects rattle, drinks slosh, and the theatre of the cabin makes a modest ride feel dramatic.

Structurally, the wing is built with the flex of a diving board on purpose. A rigid wing would be a brittle wing. A wing that bends absorbs and returns the load of rough air, which is why the visible flexing that alarms passengers is a designed feature rather than a symptom. Crews slow down in rough air, ask for the seatbelt sign, and often change level to find a smoother layer, all of which is comfort management rather than emergency management. The seatbelt is worth wearing throughout, not because the aircraft is at risk, but because you are not attached to it.