Learn and practice proper posture.
“Practice makes perfect,” they say.
So, if you have any problem carrying out the correct form of the body, practice it until it becomes a habit:
Proper posture starts with the alignment of the earlobe, shoulder, hipbone, and anklebone. An excellent way to get the feel of the way your back should be is to stand one foot away from an unobstructed flat wall, with back to the wall.
Then, sit on an imaginary support by bending your knees with your back and head against the wall. Next, tighten abdominal and buttock muscles in order to tilt the pelvis up in front and down in back. Keeping your back and head flat against the wall, slowly inch your feet back to the wall and straighten your legs until you are in a standing position.
This is now the correct standing posture. Finally, walk around the room, maintaining the same posture. Place your back against the wall again to see if you have held the good form.