Lifting
Our spine is stressed out a lot when we bend our back and lift any object. These can cause many back injuries if the muscles are weak.
The correct way to lift is given here. When lifting any object, hold the weight close to the body. Always bend your knees and keep back straight when griping the object. Let the weight be lifted more by knees than from back.
If you are lifting objects high above you, then get a stool so that your spine does not arch. And always keep the object close to you as there is less stress on the back and less effort involved as well.
Sitting
Sitting puts a lot of pressure on back, even more than standing does. So it is always advisable to check out the ergonomics of the chair.
Always go for office chairs with back support. Make sure the chair is not very long as this can cause problems for the back. Let the chair have arm rests at sides.
The seat rest should be firm and it should be at a height where the knees can be supported by ground. If the feet do not touch the ground, add a stool or prop so that the knees are in level with hips.
A work chair which can be tilted or inclined, is the best friend for back as it relaxes the back muscles.
It is a good idea to take frequent breaks from work and indulge in some stretching and moving at office.
Exercise
Include aerobic and strength training exercises in the week. Go for back strengthening exercises which develop strong muscles. When muscles are strengthened, there is very less chance of the back getting a spasm.
