Should you stretch before or after a workout?

After, or on its own. Long static stretching before training temporarily reduces force output and does not reduce injury risk, so it is a poor warm-up. What works before is a general warm-up that raises temperature, followed by dynamic movements through the range you are about to use — leg swings, arm circles, bodyweight versions of the lifts. Static stretching is best kept for after training or a separate session, when it does improve range of motion over time. If you sit all day, hip flexors and chest are usually the highest-yield targets.