I just read an interesting article in Psychology Today about posture: “Straight Up. Don’t Be a Slouch.” I agree with parts of it, but not all. Here’s the link to the article:

https://www.psychologytoday.com/articles/200611/straight-dont-be-slouch

Here are some of my thoughts about it:

Holding tension at the belly button can lead to excess tension. Be careful with this. Plus you don’t need your abs to support your rib cage. If your spine is in a column, the ribs will have plenty of support.

The chest stretch is good. Most of us need stretches like this for the chest/shoulders.

Hamstring stretches are very important, especially if done without rounding your back!

Squeezing the shoulder blades together is also a good exercise to tone the right back muscles.

I agree about the backpack idea – being symmetrical helps. Regarding an ergonomic chair – that is a “wild card”, as many of them will actually make your back curvier. I do teach workshops at furniture stores, so we can go check out which chairs are really good for your back. Often the cheaper ones are actually healthier!