Please choose the correct ending to complete the given sentence: Health: [header] How to exercise your back [title] Talk to your doctor. [step] Always talk to your doctor prior to making any changes to a workout or starting a new workout. This is especially important if you're recovering from an injury or have had a history of a back injury.

Ending1: [substeps] If you plan to do the exercise again, do so once you've recovered and are reasonably strong. Your doctor may refer you to a certified professional, or they may do a physical check up to rule out the possibility of a medical reason. Ending2: He or she may help you develop your medical history, make recommendations, and suggest any new exercises you should work on. [substeps] Keep in mind, your doctor may discuss which treatment is right for you, but be aware that there is no hospital where you can see a physical therapist. Ending3: [substeps] Always get clearance from your doctor before starting to work your back. Ask her when you can start exercise, what type of exercise, what resistance weight and if there are any other restrictions. Ending4: Sudden changes to your activity level can have serious effects on your health. [substeps] The first steps are to talk with your doctor before changing your activity level.

Answer format: ending1/ending2/ending3/ending4