When doing some of the poses that make up basic hatha yoga, you should never feel pain. You must breathe deeply and naturally as you do the asana. As you breathe and move, the poses will come more naturally. You should never strain, but gently increase your ability to complete and hold each pose. If a pose feels difficult or painful, stop immediately and try it as you feel more secure and focused. If you already have any severe back or neck injuries or issues, you should check with a doctor before you try to do any yoga poses or techniques.