People normally begin to think in terms of training and injury prevention only when they have been repeatedly injured, and have had to endure pain, lengthy rehabilitation, and reduced function and performance. Most weekend warriors do not understand what fitness is all about.
True fitness encompasses strength, endurance, and flexibility.
True fitness can only be achieved with proper attention to nutrition and proper hydration. Those who embrace fitness, many times exercise in an uneducated fashion. Lifting too much for the sport you are preparing for. Lifting heavy weights and few repetitions for tennis or golf. Lifting that creates muscles imbalances.