I'll second this. I had severe back pain in my late teens due to growing 8" in one year. I didn't have the back muscles to support the new weight of upper body. I started weight training pretty regularly and don't have any problems now, at 31.

I will add that when you start weight training, make sure you do face pulls. Setting at a desk all day causes your Rhomboids to lengthen and become weak. Face Pulls will really help strengthen this muscle.

https://www.youtube.com/watch?v=MiRAi2KOfRQ