Are you constantly worried about how people are perceiving, judging or looking at you while you are acting either on set or on a stage? If you are, the potentiality to how great your performance could be will be low.
Don’t be so hung up and busy with trying to meet every requirement you think will make your performance be at the top. Do you know why? It’s because most likely, you’re trying to depict real-life characters, and the majority of people do not have a camera following them around or others watching them artistically, so the average human is not worried about how others around perceive them day-to-day. The fact you know you are being watched can test your skill, confidence and nerves. It’s that intimidation that will cause distraction, and that is a risk of driving away the ultimate realism and natural sense in your performance.
So, take a deep breath, and don’t focus so much on how you want a particular take to go to the point that if you don’t think it goes your way, the whole take is spoiled. Usually, it’s those scenes you feel like you did horrible in are the ones that are the best (at least it works that way for me a lot)…
Most importantly, try not to worry about what others think. Remember, you’ll never know anyway what people are really thinking, as thoughts circulate out of each of us every single second favorably or unfavorably whether you like it or not.