It’s a common habit for people to lean against their desks when they first switch to a standing workstation. We’re so used to furniture supporting us that we no longer have the strength to hold ourselves up for very long. When you thrust your pelvis in front of your body you are resting on your psoas like a seatbelt. This can lead to psoas tension, neck and back ache, fallen arches in the feet, and pelvic floor issues.
In the photo below, I’m…
1. thrusting my pelvis forward
2. My head forward
3. The computer screen is too low
4. The keyboard is too high
5. I’m sleeping on the job
As my old boss used to say, “You have time to lean, you have time to clean.”

In the second photo, I’ve made the following improvements…
1. ears over shoulders
2. Hips are backed up over the midpoint of knees and ankles
3. The computer screen is at eye level (the one on the wall)
4. The keyboard is lower, so the shoulders can remain relaxed
5. I’m able to stay awake because I have better blood flow to my brain

BTW, you can NOT stand aligned if you have heeled shoes on. Read more here.
You may also be interetsted in Standing Desk Exercises.