Why thinking "I can" or "I can't" it's a self-fulfilling prophecy?
Our beliefs have a strong impact on our actions and our actions shape the world we live in.
Our thoughts and beliefs influence our behaviours, and our behaviour impacts on our external world. Thinking that you can will unlock your potential you’ll have postive self-talk, you will not be scared to fail because you know it's part of the learning process together with feedback. You are therefore more likely to do new things taht will stretch our abilities. This is going to increase your confidence and keep you motivated giving you a competitive edge. While on the other end if you think you can't, you will be decreasing your chances of success because you’ll be less likely to do all the above and you could feel helpless which is going to further feed the negative vicious cycle just like positivity is going to feed the vicious cycle of success.