When you're an introvert—even a hybrid introvert/extrovert—you will run into moments when you hit a wall. The charisma that carries you will simply be gone. You're in full retreat.

This is normal. No matter how much your performance depends on it, you will be forced to withdraw simply because your spirit has to recover. 

Naturally, in the television industry, there is no time for this until your days off. I've found myself in the not-uncommon position where my off-days are being split. It's necessary and I'm all in when at work, but this proves to be even more taxing. 

You cannot use this as a crutch, though. What can you do? 

First... It may feel like a low point. It's not. When you remember that your personality works in cycles, know that you're due for the recharging cycle. 

Then...you fight through it.  Do not fall on your introversion when it's your energy that elevates your work to a greater level. It will be uncomfortable. It will be difficult. It will be worth it.

Then...do what you must to reload. Relax. Read. Watch something. Sleep. Whatever you need to return to fighting form. Relish the time you have and give yourself time to internalize all you've learned and done.

You'll come roaring back in due time. Or... If you need that energy sooner, you can will yourself to action. We are most often the barriers to our advancement and growth. Remove all the variables you can, and take care of yourself. Capitlize on your free time. Introverts have limited capacity for social activity. You can work on extending it. By nature, there is no cap on how much self-improvement an introvert can dedicate himself to. In those quiet moments, focusing on areas of improvement costs nothing for the introvert. 

Have a fantastic weekend.