I don’t get how Marco stands all day at work. I’ve been trying to do it for the past 3-4 days and my lower back is aching. Aching!
If anything is aching except your feet, you’re doing it wrong.
Check your posture. Don’t lean more on one leg than the other. Don’t sway. Widen your stance slightly if it helps you distribute the weight evenly.
Are you having to lean down? If so, you’re really doing it wrong. Raise your monitor so that the top edge is a few inches above eye-level (when looking straight ahead, not downward). Raise your keyboard and mouse enough so that your elbows form a 90-degree or slightly obtuse angle.