While not directly severe, lightning kills 43 people per year based on the 30 year average according to NOAA. If you look at the list above, you'll see that most, if not all, of these activities commonly associated with lightning fatalities are preventable.
A lightning bolt is five times hotter than the surface of the sun at about 50,000° F and contains roughly 3 million volts PER METER.
The simplest way to put it: when thunder roars, go indoors.
The following paragraphs show why and how to calculate if the bolt is far enough away to be safe from a strike.
We see lightning at the speed of light, which is instantaneous on the scale of being within even 100 miles of a storm. The speed of sound is much slower, however, and travels on average one mile every 5 seconds. We can use this difference to calculate how far away the dangerous lightning is.
So here's what to do: When you see lightning, start counting and stop when you hear the rumble of thunder. Since lightning can strike over 10 miles from the storm producing it, and given that thunder travels one mile every 5 seconds, we know that if your count is less than 30 seconds you are close enough to get hit. After the last rumble of thunder or bolt of lightning, wait 30 minutes before going outside again to give the storm enough time to move a safe distance away from you.
Safe places from lighting include enclosed buildings and hard-topped cars with windows up. The best place is inside a building away from windows.
When in a building, avoid using wired electronic devices or running the sink or shower as lightning has been known to strike homes and travel through wires and pipes.
Again, anywhere outside during a thunderstorm is unsafe.