The previous article talks using the lumbar support on your chair to sit in a "Relaxed Stance". Relaxed Stance PART•1 This allows the the spine to be positioned neutrally while being supported, which helps rest your postural muscles from more active work positions.
If you want to use neutral posture while in a more engaging work position you can use what I call the "Action Stance". This technique positions you more forward on the seat and uses engagement of your postural muscles to promote a more productive work session.
In the action stance start by positioning your rear and thighs on the front 1/3 of your seat which can enable one leg to drop downward in more of a "Split Stance" leg posture.
Next create a slight arch in your low back which will position your pelvis neutrally, now back off that arch with slight abdominal engagement to counteract the low back arch and bring it to a neutral natural low back curve. (note if there is any pain or you suspect prior back injury to consult your chiropractor or other medical professional)
This engagement of your back muscles by creating a curve and subsequent engagement of your abdominal muscles to counteract and maintain neutral posture is called "engaging your core muscles". This is very popular term in fitness, especially in the past two years. However it's important not to just flex your muscles haphazardly, but engagement of core muscles while supporting a neutral spinal curve which (for the lumbar spine is a slight forward/lordotic curvature).
Next, bring awareness to your mid back and how it rests upon the stable support structure we have just created. The shoulders rest upon the mid back curve. Bringing your shoulders upwards, them backward, then relaxing them downward, is an easy protocol to bring your shoulders (back and down). This helps to relax the often over stretched and weekend rhomboid muscles.
Finally centering your head on top of your spine while avoiding too much forward translation can help promote relaxed neck muscles.
Now when you lean forward to do computer or desk work, lean from the hips and not the back. Also notice how you are feeling in this more upright posture, how clear you are thinking, and how your motivation for the next work task may have increased. This posture is a "Doers" posture for people who don't intend on waisting time and want to get quality work done, with out being distracted by mundane idiosyncrasies, or old time wasting habits. This is why I named this position the "Action Stance", it is the position favored when work needs quality succinct solutions.
Learning to have natural posture takes time and does require using a bit of finesse to find your comfortable position with in neutral posture. Now this positioning may feel unnatural or awkward at first, now comes the part where having a professional can help enhance your natural posture. There are many professionals that help with posture in general. I specialize in helping workplace professionals, and business professionals have better posture in these environments. Innovatio Health in the Silicon Valley Other professionals may also be beneficial such as teachers of Alexander Technique, or Gokhale Method.