This is a topic that I struggle with: posture. It is always present, sitting, standing, heck, even sleeping.
The key here is to keep your spine neutral. That's why standing is so preferable to sitting. That said, if you do sit, you want to be upright with minimal stress on the joints.
Similarly is when exercising. Keep the posture in play to maximize performance and avoid injury.
Give yourself a reminder with notifications, have someone take a picture or video to hold you accountable.