Did you know that as of this year, low back pain is the number one cause of disability worldwide? Also, the majority of low back pain is mechanical in nature - meaning it is not caused by serious conditions such as cancer, infection, fracture, or inflammatory arthritides. Most back pain is actually due to one or any combination of acute trauma (i.e. fall, contact sport injury, etc.), poor posture, and low levels of physical activity (sometimes followed by physical activity exceeding the capabilities of the individual - "too much, too soon").
If you've been advised to rest until a bout of minor back pain has healed, you're likely doing more harm than good! It is important to stay active while recovering from an injury, while making sure not to over exert yourself. At the end of the day, those with mechanical low back pain who maintain a higher degree of activity recover quicker with less likelihood of re-injury.