A cleverly designed warm-up will improve performance and also improve mobility helping you to achieve proper technique and posture.
Stretching will improve your flexibility and mobility. These enhance your range of motion and ability to apply the proper technique to exercise.
The reasons as to why proper technique is essential are clear; to minimize your risk of injury and to optimally target the muscle groups you want to work.
Valsalva belly breathing is where you breathe down into your belly and push your belly out while using the Valsalva maneuver.
There are many elements to injury prevention. If you want to exercise safely or overcome injury, you will need to heed the wisdom of others.