At the end of a workout, the last thing most people want to do is stretch and cool down. If they do dedicate time to stretching post-workout, it usually involves a few simple toe touches and some arm swings before heading for the smoothie bar. As you perform contraction after contraction during your workout, your muscles are left in a shortened state. Stretching helps to reset your body to a natural position and posture. Walk out of the gym without paying attention to areas that are overly tight, and you may pay the price later on with increased soreness and stiffness.
One important note: not all muscles need to be stretched post-workout. Focus on hitting only those areas that are exceptionally tight either from the workout or from daily posture.
Static stretching is only part of a good cool-down routine. Along with stretching, put some light walking and foam rolling at the end of your workout. This will help increase circulation and lower your heart rate slowly instead of heading out of the gym immediately after your last set. A cool-down routine will also decrease post-workout soreness.