You're a classic case, she said. I think I may know what's causing your pain and I may be able to help. She then explained that an average person's arms weigh about 14lbs.
When you sit all day using a keyboard and mouse it's very important to have arms on your chair. But not just any arms. They need to be padded, adjustable up and down, and most important, they need to be able to pivot in, so you can get close to your work.
You also need a foot rest. This will give you something to push against and remind you to lean back, and always have full contact with the back of your chair.
This will promote good posture. Let the back of the chair support your back. Relax.
I said that my physical therapist told me to take the arms off my chair. Cynthia replied that most office chairs have arm pads that are hard plastic, stick out too far, and are not adjustable. They are useless. So people recommend you take them off, so you can get close to your work.

However, if you hold your arms up all day unsupported, it affects your upper back, shoulders, and neck. Also, if you rest the weigh of your arms on hard surface you run the risk of developing carpal tunnel syndrome. It's a problem a lot of people have with their chairs. They spend a lot of money on an "ergonomic" office chair that has useless arms.
To be useful, she repeated, they must be padded, adjustable up and down, and most important, they must pivot in. This allows you to sit "in your chair" not just "on your chair."
If you just sit "on your chair", you might as well just sit on a stool, a ball or a kneeling chair, which are ok, if your up and down alot, and not sitting for hours at a time.
She explained more and more people are coming in with shoulder pain, upper back pain, and neck pain, from sitting all day on a ball, and holding their arms up.
Balls are great to strenghen your core, and they are OK sit on for short amounts of time.
She then said she would give me a price quote, so I could go home and think about it. No hard sell at all. I asked, what if I bought the chair and didn't like it?

Cynthia assured me that if I got a new chair with these great arms and used the chair correctly with a foot rest, that if it didn't help make my pain go away, I could bring the chair back for a full refund. No questions asked. I was very skeptical. She's a sales person just trying to sell me something. I was very cynical. She said if I didn't love, love, love the chair, please bring it back. It's OK. It's no problem. So long story short, I purchased the chair. I started to feel less pain right away. After 2 weeks I was pain free. I can now sit all day without pain. It's so rare these days to get a product that lives up to all the "hype".
I was truly surprised at the wonderful outcome. I had no idea a chair could make such a difference in how I feel at the end of the day. In a word, amazing.

The time and money I saved by no longer needing physical therapy has paid for the chair.
I thanked my physical therapist for sending me to the Better Back Store of Boulder and she is happy that I discovered the source of my pain.
She was glad to learn about how seated office workers can truly benefit from a true ergonomic office chair. I highly recommend the Better Back Store of Boulder.
They are knowledgeable, helpful, and friendly. No hard sell.
They are happy to educate customers about office ergonomics.

I am a very happy customer.
Karen, from Boulder