Concentrate on proper form and technique. Exercise at a pace that is comfortable for you. When weight training, it is better to use lighter weights and do more repetitions, than use heavier weights and risk serious injury. You are not in the gym to impress anyone, you are there to achieve your goals. Injury will prevent you from achieving your goals.
Some athletes try to continue training a body part after it is injured.
It is absolutely necessary to properly treat and rest an injured area in order for it to heal. This type of mentality will only make the injury worse and prolong your recovery time. Trying to train through an injury can lead to permanent and disabling problems which will remain with you for the rest of your life. Later in the healing process for sprains and strains, moist heat and ultrasound can be used after the swelling has subsided. Heat and ultrasound are vasodialators and will increase the blood supply to the injured area.