One of the most common causes of back pain and injury is lifting heavy objects improperly. The most important thing to remember when confronted with a heavy item that needs to be moved, is to lift with your legs, not with your back.
The old adage, "Put your back into it," really should be "Put your legs into it." Squatting down to be nearer to the object and picking it up as you stand with your legs reduces stress and strain that hoisting can put on your back.
Be especially careful not to lift and twist or turn at the same time. The two actions combined put your back at risk for serious injury. Bend at the knees, lift the object up and turn your whole body with your feet. If you are lifting something heavy with another person, be sure to coordinate your movements in unison.