Apple watch counting steps whilst sitting

Hi, I recently purchased the Apple Watch series 3, 42 mm.

I have noticed that the watch counts a number of steps whilst sitting, for the last two hours I have been lying in bed on my laptop, but my watch has counted over 300 steps? WITH NO MOVEMENT WHATSOEVER.

I have read other posts that talk about calibrating the apple watch, which was no help seeings as all my default setting were already turned on.

It is a really big pain, seeings as I need the data that specifically surrounds my steps. After paying so much for the watch you would think this feature would be 100% accurate :/

HELP