Recently, I found that building a habit of push-ups is essential for a sustainable academic career. Keep the strength in waist will help one to sit straight and minimize energy loss coming out of a bad sitting posture. From the word of a health advisor in Harvard [1], it is impossible to maintain the subtlety of being able to maintain the body in ideal postures without a basic amount of core strength. Even for workout of push-ups, it is by no means possible to do in standard position without a certain period of training time. And it is still worthy to keep going with bad position, just to turn the basic core strength into reality.
PS: This way of workout applies in many other fields.