Anyone can have back pain. Factors that can increase the risk for low back pain include:

Age:

People usually experience back pain when they are between the ages of 30 and 50, and aging can increase the risk of back pain. Weakness of bone structure due to osteoporosis can lead to fractures, moreover, muscle tonicity and flexibility will decrease by age. As you grow older, the discs in your back begin to lose water content and degenerate which can make the spinal vertebras vulnerable to spinal stenosis. 
Fitness level:

Weakness of the back and abdominal muscles in people who are not physically active can cause back pain as these muscles are not able to support your back. Activities and exercises must be done continuously and accordingly, otherwise, the sudden activity after a long time could cause injury and pain.  

Obesity:

Being overweight, obese, or quickly gaining significant amounts of weight can put pressure on the back and lead to low back pain. 

Genetics:

There are a few genetic-related problems that can affect the spinal area and cause back pain, such as ankylosing spondylitis a genetic form of arthritis, which can cause lower back pain as spinal joints fuse together. 
Structural: Scoliosis is an abnormal curvature of the spine that can cause low back pain, especially in adults.
Job-related factors: Job-related back pains are common, especially jobs that require lifting heavy materials, pushing or pulling or twisting the spine can lead to injury and back pain. Jobs that require sitting for a long time can cause back pain due to bad posture, less support, and more pressure on the lower vertebras and muscles. 

Mental health:

Stress, depression, and anxiety can affect the body in different ways, including causing muscle tension and spasm, poor diet, and less activity and mobility

Smoking:

Smoking can cause the discs to degenerate faster, as it will decrease blood flow and oxygenation to the discs.
Backpack overload: Carrying heavy backpacks can strain back muscles, make the posture inappropriate and it can lead to back pain, neck pain and shoulder pain. The backpacks should weigh less than 20% of the kid’s weight.  

Hamed Shakiba 
Medical doctor (Iran) 
Osteopath (Montreal) 
gorendezvous.com/shakiba