[realtarget]

Well, to be honest, nearly all other answers say: Search a new job. But this will be just an escape from a usually solvable problem.

Just try to speak to your boss and tell him your wishes and demands. A satisfied worker is always better than somebody who resigns or burns out.

[amiburntout]

I was considering something like this. I guess I'm worried that saying I can't handle the workload will make me less likely to be looked at for new projects. Have you, or anyone else reading this thread, had success with a conversation like this and have any pointers?

[realtarget]

Not me in person, but a colleague. The boss was very open minded and told him that he did not recognize that he was overloaded. It's important to differentiate between overchallenged and overloaded. You seem to be overloaded but not overchallenged - and this needs to be communicated to your prinipal (absolutely certain!).