Fun fact that I've recently learned: Ergonomic office chairs, especially those meant for productivity (as opposed to pure soft comfort for 24-hour jobs), are largely designed around *encouraging* mobility. The amount of things that are beneficial about staying in motion while resting are absurdly numerous considering how many of us would probably be inclined to guess that the healthiest way to sit is to find the "optimal" posture for your spine/shoulders/neck and stay in it.

There are specific things a good chair can do for your posture besides just padding and keeping you active (personalised measurements for things like lumbar support, breathability, etc.), but much of the benefit is just generated by what it encourages you to do for yourself.

Now, lying/lounging on the ground or a sofa while reading aren't quite the same thing as sitting in a chair to work, so you don't have to expect quite as much motion to be necessary. More akin to sleeping. But I'd still suggest steering clear of trying to establish specific perfect positions.

Your instinct tells you what your body wants, and even if you never put any weight or restrict bloodflow to any part of your body, chances are staying in one position for a long chapter isn't the way to go.

Not sponsored, I just really liked the way my body felt after I sat in that boutique for less than an hour.