Good posture

If you work at a desk, avoid slouching, and don't get stuck in one position for hours on end; it's bad for your posture. Change your position: don't bend over your work all the time, but lean back when you're reading through something. Sit up straight when you are typing.

When you're sitting at your chair, try to keep your shoulders straight. From time to time you should stretch your neck muscles and relax your shoulders. Tilt your chair forward so that your knees are lower than your hips.

Keep both feet flat on the floor, Not pulled back under your chair. Crossing your legs will twist your spine and put pressure on your knees and hips. If your feet don't reach the floor, put them on a low stool.

Finally, make sure that your chair is adjusted to the right height so that your eyes are level with the screen.

Vocabulary
slouch  verb [intransitive] 
      to stand, sit, or walk in a lazy way, with your shoulders bent forward
      slouch back/against/in etc
      • Jimmy slouched back in his chair.

get stuck  become unable to move

on end   without stopping; for hours / days on end.

posture   the way you hold your body when standing  or sitting.

bend (over/down)   move the top part of your body forwards and downwards.

lean (back/forward)   bend or move your body from a vertical position

straight   not curved or at an angle

stretch sth   push a part of your body out straight: stretch your arms.

tilt sth   move sth so that one end of it is higher than the other end.

cross your legs   place one leg over the other.

twist sth   bend sth in an unnatural way.

spine   the row of bones down your back. backbone.

reach sth   be able to touch sth.

adjust sth   move sth slightly so that it is move comfortable or in the correct place.

level with sth   having the same height, position, etc. as sth else.