As far as your posture is concerned, the most crucial and primary relationship is the relationship between your head and spine.
The adult head weighs between 8-15 lbs.
Find something that is 10-12 lbs. A medicine or bowling ball will work. A gallon milk jug filled with enough water to weigh 10-12 lbs will work as well.
Hold your object in front of you so it touches your chest. Experience its weight. Now, extend your arms so that your object is away from your body. Experience its weight. If I asked you to hold your object for 10 minutes, where would you want to hold it? My guess is close in near your body would be your preference.
Your head consists of two parts (1) your skull and (2) your lower jaw. The skull balances delicately on the top vertebra of your spine right between your ears. Yes, that high up! The lower jaw is suspended in front from the skull.
The joint between the skull and spine allows you to nod your head up and down—to look down at your computer keyboard or up at that spider on the top of the wall. I like to call it my Nodding Joint or alternatively my Looking Up Looking Down Joint.
Take your pointer fingers and stick them in your ears so they are pointing towards each other. Imagine a rod connecting your two fingers. Allow your head to gently pivot around that rod so you look up and down a bit. That is where your head is designed to nod from. Yes, that high up!
Now take your hand and place it at the base of your neck in back. The seventh cervical vertebra is a little larger and sticks out a bit more so you can usually find it easily. This is where a lot of us mistakenly nod our heads from.
Imagine you are holding your smartphone in front of you and look down from that seventh cervical vertebra so that you are dropping the head and neck to look down. Now try looking down from higher up where you now know the joint actually is—between the ears. It should be a much lighter feeling (you might have to move your smartphone to do this easily…)
The difference between looking down from higher up at the actual joint, high up between the ears, and from the base of the neck is similar to the difference between holding your object close to your chest and then extended out in front of you. When you can leave the weight balanced more on top of its supportive spine instead of letting it drop in front of its support, it will be lighter and cause less strain on your body.
Take some time to explore where you are habitually looking down from.