We can't know for sure exactly how we're going to die, but some ways of going are more common than others. The National Safety Council in the US has calculated the probability of dying from a variety of causes in this interesting graphic.
The largest box is the odds of dying from any cause: 100 per cent (because we're all going to kick the bucket some day). The two least probable events have the smallest boxes at the bottom: dying from a cataclysmic storm or from lightning (1 in 126,158).
It's worth noting that these lifetime odds of dying are statistical averages over the entire US population and don't predict your or any other individual's odds of dying from a particular cause. Still, it might be comforting to know that you're less likely to die from an amusement park ride than you are just walking around as a pedestrian. (Roller coasters aren't on this list, but Consumerist reports numbers from the Consumer Product Safety Commission: in 2011, of the 1.7 billion rides taken, only 1177 people were admitted to a hospital or died from one of them.) Bigger things to worry about, it seems, are getting regular medical checkups, particularly if you have a history of cancer or heart disease in your family, treating or preventing depression, and maintaining the healthy lifestyle habits.
Here's the full graphic (click to expand or right-click to save):
The Odds of Dying From... [National Safety Council]