Make it look easy!
When working out, we try to look like we are working hard and a lot of people end up with the “pain face”. Note that facial tension actually degrades your performance. Look at most of the great athletes: they look relaxed and they move seemingly effortlessly.
By practicing relaxation, posture, breathing and control, you will look just like a pro.
Create tension where you need it, relax where you don’t.
Here is a great blog post by Dr Eric Cobb: Avoid the Pain Face