i'm beat - A way of saying you're not weak, you're just tired and ready

A way of saying you're not weak, you're just tired and ready to drop a swear word.

I'm beat, but I'm not giving up, I'm just going to cuss you to sleep.

I'm beat, I could take a nap, but I'm still going to cuss you to sleep.

I'm beat, I just ran a marathon and I'm still going to cuss you to sleep.