Why does my Apple Watch asks me to stand up when I am already standing up?

Hi

For the purpose of crediting the hourly Stand achievement, your watch aims to identify when you have stood up and also moved around for at least one minute during that hour.

Apple Watch uses an accelerometer to identify movement, so arm movement equivalent to changing from a seated to a standing position followed by a minute's walk around with your arms swinging naturally should help to register this.

Stand credit can be earned once within each hour. If you have not earned credit by 10 minutes to the hour, then Apple Watch provides a reminder.

Calibrating your Apple Watch can improve the accuracy of estimations made by Activity app (and Workout app). Instructions are available via the article below. Resetting calibration data does not erase Activity history.

More information:

Use the Activity app on your Apple Watch - Apple Support

Calibrating your Apple Watch for improved Workout and Activity accuracy - Apple Support

Mine does this too. I can be up walking around the house. Feeding dressing kids etc and 200+ and 15mins later apparently I haven't been standing and active long enough! VERY annoying! I'm loosing credit of hours "standing" during the day. And let's just say as a mom of 3 my normal day is 17hrs and I don't sit down for any period of time much less a hours worth!!!!