By seeing or imagining others model successful or unsuccessful responses in specific situations may give us confidence or the jitters. Other people could also model for us how to solve problems and accurately form efficacy judgments by talking aloud as they solve problems and compare their effectiveness with others. We could hear how others think, how they assess their ability. Interestingly, it is probably much easier for negative feedback to undermine our confidence, than for encouragement to build it. It is harder to be successful than to fail.
Persuasion is the approach of the super salesperson or the efficiency expert.
A good mood and a healthy, comfortable body generate positive expectations. You also choose to do whatever you do. What is not clear, yet, is how much obtaining these outcomes in life is responsible for raising your faith in your ability to control your life vs. how much the faith alone should be given credit for producing these outcomes. Clearly, it works both ways. So, raising your self-efficacy is a good idea, but there have to be accomplishments too.