Lifting injuries are a common cause of back pain. You can protect yourself against damage with good lifting habits, both at home and in the workplace.
Five Steps to the Correct Lifting Technique

1) Place your feet shoulder-width apart.  
2) Bend at the hips and knees.  
3) Grip load firmly and keep it close to your body.  
4) Use the strong muscles of your legs to lift.  
5) Keep your back as straight as possible during the whole lift.

Safe Lifting

Make Your Work Easier
Always check the weight of the load and get help if necessary.  Wherever possible, lift and carry heavy items with a crane, hoist or forklift. Instead of carrying parcels, use a hand trolley.  Repackage heavy articles to reduce the size and weight of individual loads.  Wear comfortable clothing and flat, non-slip shoes.  Store loads that you move regularly at waist height so that you don't have to bend your spine or lift overhead.  Make sure that the pathway is clear.
How Lifting Can Injure Your Back
When you lift, your back is put under stress.  Twisting or jerking while lifting and carrying can injure the small facet joints which guide movement of the back.  The discs which separate the vertebrae (spinal bones) and the ligaments which hold the vertebrae together are also at risk. The discs are composed of a jelly-like core, surrounded by a strong fibrous ring.  With repeated unsafe lifting, the fibrous ring or its supporting ligaments may tear or rupture.  

Lifting while bent forward will increase the stress on your spine. Contributing to this stress are factors like the weight of the load, how far it is held from your body, how often and how fast you lift and how long you hold the load.

Why Fitness Helps
Your physical condition is important. For example, stiff joints and muscles can reduce your ability to keep your back in a safe position as you lift. If your leg muscles are not very strong, you may find it hard to crouch down. Poor fitness will cause your muscles to tire, placing more stress on your spine.