Whether you've been an athlete since you were 6 years young, like myself, or someone new to fitness, the last thing you want to do is get hurt while working out. Summer is upon us. No one wants to be "That Friend" who gets hurt/injured and misses out on all the Summer 16 festivities. The best way to prevent injuries is to implement a dynamic warmup and static stretch as part of your pre or post workout routine.
Dynamic warmups involve active tightening of muscles to move joints through their full range of motion. Functional and sport-specific movements help increase muscle temperature and decrease muscle stiffness. In short, dynamic movements prep your body for optimal performance. Warming the body up with some light cardio or dynamic movements (see above video), prior to exercise, is extremely affective in preventing injuries.
Our body contains a lubricant called Synovial Fluid. Synovial Fluid sits in your joints (just like a car has oil that sits at the ready), to ensure that all of its components operate effectively. When gently heated up prior to rigorous movement(Running, Football, Basketball etc), will help prevent injury and ensure optimal performance of your body's connective tissue.
Static stretching muscles and connective tissues can also help to prevent injury. Keep in mind that your body is a lot like a car (or SUV) when it comes to movement. The more you warm it up, the better it operates. Static stretching requires you to move a muscle to the end of its range of motion and maintain it without pain for about 20 to 40 seconds. 
So the next time you're getting ready to workout, remember to stretch and warmup. You can't be cool or cute while on crutches. If you're performing a sports related activity (running, basketball, swimming), I would start with a dynamic warmup. Then once you're finished your workout, cool down and relax with some Static Stretches.