Is there any way to prevent myself from becoming exhausted after spending a short time talking to the general public?

I'm a university museum administrator and professor. I am talking to people ALL day long. Either I'm lecturing in class or to a museum audience, or I'm giving presentations in meetings, or I'm doing private tours for donors or other special groups. If a regular tour guide can't show up, I'll fill in. I've been doing all this for years.

So, I'm wondering if a job in which you have to give tours and speak to the public is really the right one for you. You don't sound as though you like it much.

I suggest that you make sure your mouth doesn't get too dry, so rinse with something like Biotene and stay hydrated. Use plenty of lip balm to guard against cracked lips. As for smiling -- well, that's just part of the job.

When you're not doing tours, stay as quiet as possible. Tell your friends and family that you're instituting "quiet hours" during which you will not talk. Stay off the phone; rest your voice and your mouth/throat.

Otherwise, you might want to look for another job.