When we want to consider posture then we do not pay attention to the body. You can correct posture by doing activities like exercising, taking sound sleep and avoid use of substances like tobacco, alcohol, drugs.
You may try to get correct posture but only few people can achieve it.
Do Exercise To improve your body structure
You can add exercise to the daily routine and perform it for 30 minutes. You cannot overstrain yourself with light yoga.
Adjust Your Seat According To Your Back
You can adjust your back when you work for long time. You should make the back straight and adjust the screen of computer as per level of eyes.
It is necessary that your neck should not be bend as per the level of screen.
Hold your Phone in Correct Position
You should never bend your neck while using mobile. You should hold the phone in front of eyes and laptop at right angle while at sitting position. Children usually have habit to watch a cartoon or play games which may bend their neck.