My Apple Watch has a full green circle but is dead in about 2-3 hours

If you purchased this brand new 13 months ago, it shouldn't be running out of charge in 2 - 3 hours. Which Apple Watch model is it? Something is likely running in the background, which is draining the battery.

This link might help you --> Apple Watch Battery and Performance - Apple Support

I would also perform a Forced Restart on your watch: Press and hold BOTH the power and digital crown at the SAME time (keep holding past the screen going black) until the Apple Logo appears, the let go of both buttons.

How old is your Apple Watch? Batteries lose battery health with every full cycle charge, so depending on the age of your watch, it may be nearing the end of its useful life.