"An ounce of prevention is worth a pound of cure" - Benjamin Franklin
Most accidents happen for a reason.
Serious injuries occur when we fail to take proper safety measures. In today's world we move at incredible speeds and when we collide the impacts are immense. That's why cars are made of durable materials and come equipped with seatbelts and airbags. We where helmets when riding and padding in contact sports. Even then injuries happen. Mindless actions, defective parts, and improper usage are the causes of accidents. Weaknesses, imbalances, inflexibility, and structural misalignments are cause of injury.
Injury = [Impact x Quantity] / Time
Injuries can be seen as a mathematical equation where the severity equals the level of impact times the number of times it occurs divided by amount of time. An acute injury comes from a potentially high impact multiplied by (hopefully) a small # of instances over a short period of time... like a car accident. A more mild-chronic condition can arise from low level impact with frequent occurrences over an extended time-frame... like repetitive stresses from working at a computer. While we often take precautions for the more serious injuries, we may overlook the chronic-repetitive ones as they have lower initial impact and are often frequent enough to become habit and dwell in the subconscious.
Mindfullness amongst the mayhem.
Becoming aware of potential threats (big and small) is the key to creating conscious choice points to prevent injury. Most accidents happen close to home. People feel most comfortable and safe at home and in their quiet neighborhoods leading to a 'dropping of the guard' otherwise known as mindless or unconscious behavior. This is good when you are sitting on the couch, but not so good when backing out of the driveway or standing on the edge of your chair trying to change a lightbulb. By slowing down and maintaining a mindfulness about your body and activities you can avoid most accidents.
That said, accidents do happen. Being rear-ended or having a foul ball hit your in the head are hardly your fault and even the most mindful beings can get hurt. This is where we focus on solutions rather than fear problems. Being mindful and creating a more resilient mind is probably your best tool to avoiding injury. Next is working to make your body (inside and out) more resilient through proper conditioning (think endurance, flexibility, and strength) as well as by addressing pre-existing weaknesses and imbalances. Your ability to positively affect yourself can help to offset your inability to anticipate or prepare for the unknown.