You only get one back, and anyone with back pain will tell you its health isn't something to take for granted. One important goal when lifting is to do so without adding stress to your spine. The most vulnerable place for injury is your lower back, and your neck, shoulders, elbows, hands and wrists are also at risk.
Be aware of your body. When lifting, your knees should be bent and your back should remain straight. Keep your back straight from the time you lift to the time you're done lowering the object. And while you're carrying the load, keep the object you're lifting close to you, and don't twist or reach while you're lifting.