If you are an actor, dancer or musician, there is one key thing that is asked of in your profession, and that is confidence. For me, as an actor in training, I have found it extremely difficult at points to battle my nerves and be confident in what I am doing. When I first started acting about ten years ago, I was a nervous wreck going onto stage each night. Now I believe I have learnt what the perfect balance is between nerves and confidence. However, you can see the difference in someone battling with their nerves and someone who is too confident for their boots that it spoils their characterisation. And yes, there is a thing of being too confident when approaching a character.
Having confidence is great, it means that you are comfortable on stage, plus nerves most likely won't show and affect the character. However, with confidence, I believe it is healthy as a performer to have nerves, it gives you a little bit of adrenaline to add some energy to the performance, no matter what production you're doing. Also, as an actor it is vital you critique yourself, not overly, but just enough to make sure your performance is the highest quality it can be. It is fair enough to make sure you help others out if they ask for notes, however, when it comes to your own performance, you need to be open to criticism.
Having too much confidence numbs people from seeing their flaws as they are that comfortable with themselves and believe they are very talented. Which means when they are given advice from fellow performers, or even the director, they retaliate. Actors usually give an explanation into why they have followed that specific characterisation route, which is all well and good, but if it isn't working, then listen to your fellow castmates. Plus, definitely listen to the director, it is their vision, you are working for them. I would advise people to listen to others, and if one person is telling you something, get a second opinion. If loads of people are telling you that something is wrong, then, it probably is. Yes, you may be talented, but, your vision for the character may not be working. It can be the said the same for directors, sometimes, because they are confident in their visions, they do not listen to their cast and ultimately set their production up to fail. Luckily, I have not faced this when performing, but I have heard some horror stories and seen some productions which seem like they have failed because the director has a complete disconnection from the cast.
When it comes to being nervous and unsure of yourself while performing or developing, it is so vital that you have people critique you, and that you listen to what they say. Within this industry, so many people hate being critiqued, because they are scared of what others are going to think of their work. However, if you are in the developing stage of a character, brilliant, listen to others, get several opinions and ask how you can improve, if the people criticising you are turning to praise you, then begin to feel confident. Don't be so nervous, you are doing a good job. I think people who feel so unconfident in performing need to listen to others, opening yourself up to criticism is the road to being praised as the criticism is telling you how to succeed.
If you struggle with your anxiety and you still cannot build confidence even through getting positive feedback, as long as you are performing well on stage, that is the main thing. For actors, it is difficult if you are looking to make it in the industry as even though you are super talented, many successful actors are huge personalities, confident to talk about themselves. Don't worry about that, with experience you will become a stronger person, believe me. Many of the best actors I know, are down to earth people, who own it on the stage with huge characterisation, but are chilled, approachable people off stage. You don't need to have big personalities like Judi Dench or Ian McKellen to succeed, I mean most actors are normal(ish) people. Just be able to balance your anxiety on stage so that it doesn't affect your performance.
If you are in training or still at school and want to become an actor, please consider this, within the industry, it is mentally and physically demanding. If you do not have confidence in performing, then please consider the fact that you will need to perform for a job, you will be criticised on a daily basis and you will be working in a highly competitive industry. You need to have an element of confidence in performing to succeed, that doesn't mean love yourself, that means you are confident that you can act your ass off to achieve the characterisation you have been set by the creative team.
If you have an element of confidence in that you know you are a strong actor and you are open to the idea of constantly developing, receiving criticism on a daily basis, able to work with others and are determined to get work, considering you will be unemployed for probably half your career, then, acting is for you. Use that element of confidence to help you, don't get too big for your boots and remember, if you've received a mass amount of praise once, you can do it again. Good luck!