Holy Shit, I just discovered how to sit up straight. I've been doing it wrong my entire life.

All my life I've wondered how the hell people can just sit at a table and just sort of... float there, no real effort expended, their spine just kinda stays upright. Whenever I would sit in a chair it always felt like my back weighed 50lbs and it would take significant effort to not flop over and lean on my elbows or slouch backwards against the back of the chair.

Whenever parents or teachers said to sit up straight, I thought it meant use your back muscles to straighten your spine.

It has almost nothing to do with your back muscles. I was sitting at a restaurant, thinking about something I learned in a class, and randomly tried rolling my pelvis backwards. Not even thinking about my posture, and all of a sudden I was sitting up perfectly, with almost no effort (other than flexing my pelvis) I actually tried to put my elbows on the table and could barely do it. My spine didn't want to bend that far. I was just floating over the base of my spine, like I had seen so many other people do.

Basically, as far as I can understand it, when your pelvis is rolled even slightly forward, the natural curvature of your spine pushes you even further forward, out past your base of support, and it takes significant effort from your back muscles to pull it back in. If you roll your pelvis in the opposite direction of your spinal curvature (backwards) the spine starts out by pointing a few degrees backwards, then the curvature naturally brings it back to center where it naturally balances between your back muscles and your core muscles. How did no one tell me this?

Maybe everyone else already knew this and I'm the last one on earth to figure it out, but I feel like sitting is an entirely different activity now.

Edit: To try to clarify what I’m talking about:

Slightly tilt your hips so the top of your pelvis is pointing up and a little towards your back or at least not towards the front. Basically what this lady demonstrates but while sitting.

Edit 2: imagine this "/" is your pelvis.

Do This: \ ┬─┬

Not This: / ┬─┬