I'm also a 40ish man, about 5'11". I was having back pain, and it has stopped. While I haven't found a perfect solution, here's what I'm doing. - Nowadays, I'm

I'm also a 40ish man, about 5'11". I was having back pain, and it has stopped. While I haven't found a perfect solution, here's what I'm doing. - Nowadays, I'm mostly using a kneeling chair. - I've also built a button chair. (See the TED talk at https://buttonchairs.org https://buttonchairs.org). I use it some of the time, and it is okay. - I also use a fairly plain wooden chair at times. Additionally, I take regular breaks (every couple of hours) and go for a walk around the block. I've also heard that exercising your core helps.