Keep your chin up and avoid slouching to improve your posture. Wear comfy shoes if you usually stand up for long periods of time.

Get up every 20 minutes to stretch. Sit in a chair that fits you correctly so that your back touches the chair and your feet are on the floor with knees at a 90 degree angle. Ensure that your computer screen is at eye level.

Sit in a supportive chair with your back against the chair and your feet planted on the ground. Get up and stretch every 20 minutes if you sit for long periods of time. 

When lifting heavy objects, bend your knees and do not lift anything that is too heavy in order to avoid damaging your muscles and your spine.

Warm up and adequately stretch to avoid pulling something if you plan on working or playing.

Use a headset or a speaker if you speak on the phone for long periods of time to avoid cradling the phone between your neck and your shoulder which could cause damage to the muscles or vertebrae in that area.

Make sure that you are in a supportive position to avoid straining your neck or back if you are laying down.