If you want to learn this science, you must be careful about your diet. Take regular and light Sattvic food. Man is much influenced by his diet. See the difference between a small lion and a big elephant. You will be able to improve yourself by adjusting your diet.
Idleness is due to a variety of rich diet only.
Therefore, be strict in your daily diet. You will be ever active and strong. Pose A man who performs Sandhya does not care about his sitting pose. He sits in any posture. This is not much beneficial.