Okay boys and girls, enough of all this nonsense. I too, like you reading this, have read all the ideas for solving battery drain on the S3. This is all you need to do.....
1. Go to SETTINGS on watch, tap it.
2. Scroll down to ABOUT WATCH tap it.
3. Scroll down to REPORT DIAGNOSTIC AND USAGE INFO tap it.
4. Switch to ON
Your problem is now solved. I know it sounds counterintuitive as it would indicate the watch would be using more juice, but it doesn't, it just fixes a bug in the watch software. Go and enjoy your new invigorated S3!