[01100011]

Each person is different, but for me weight training helped a bit with back pain and a little bit of posture, but fixing my posture is a completely separate(and ongoing) activity.

For me, good posture starts with awareness. I have poor proprioception so unless I see myself hunched in a mirror I'm not aware I'm doing it. I am a very narrow-focused person though.

The other part of posture is just working at it long enough to build a connection to those important muscles. Teaching someone to have good posture is like teaching someone to wiggle their ears. Some people were born with that control and other people just don't even know what to do, mentally, to activate those signals.

Final part is to adjust what feels 'right' so that keeping your chest out more, your head back, spinal curves not too far in either direction, etc, all feels natural. I fight with the feeling that I look like a jerk when I'm just holding proper posture.

That all said, I think focusing squarely on your lats and lower traps can be a good starting point for folks looking to fix their posture. Yes, it's more than that, but it was one thing that helped, in addition to everything above, for me.

[numpad0]

It also helps to sit on a good chair, which isn’t necessarily the most comfortable. I currently sit on a used front seat from some ~1995 Subaru, and it used to be horribly uncomfortable but it forced me so hard to face forward and upright that I eventually got used to, which likely is not too far from a correct posture. That implies how wrong I am to be on this prestigious forum - but it helped my posture far more than a comfortable chair that faithfully held my body at a “sack of potato” posture.

[smolder]

I went from an office chair with arms I would lean on, to a regular folding steel chair with a cushion on it. It has forced me to hold myself upright and has thus fixed some occasional pains I was having from bad posture.

[grugagag]

Yes, a facny chair can give you the false comfort of sitting in a poor posture and making bad habits. I prefer simple non swivel chairs for better posture and better grounding.