My face betrays me despite my best efforts. But you have to be observant or focused on me to see it. I can go undetected most of the time because most of the time people aren't paying that level of attention.
If I'm really caught off guard my face will show everything for a moment before I regain composure.
It's unnerving whenever someone sees through. Most often it's happened that someone has remarked that my eyes look sad (even though I'm usually cracking wise at the time). And they are always right. Stops me in my tracks.
Actually, I feel things through my body even when I'm trying to keep a lid on my reactions to the point of concealing them from myself. Whenever I have one of those sensations I take note and realize that I have to take seriously whatever it is that I'm reacting to.