Method Actors know this fact intimately. They study a character – the mannerisms, the voice tonality, the gait, the tics – and they assume that behavior. Actors that do this really well change their whole lifestyle into what they believe that character would live like. Whether or not the character actually did/does live like that is immaterial – if it guides their subconscious mind into directing their behaviors, it does the job.
You can apply this to real life as well – growing characteristics of your own that you admire in yourself, or assuming characteristics that you admire in someone else. What happens is that you see your behavior objectively and area able to adjust it over so that you fit that archetype. If you present an image to yourself of high-esteem, your subconscious mind will automatically make decisions that encourage that image to exist. Before making a decision, you will think to yourself “is this something that I do?” – and then your behavior fills in the blanks. Setting up an archetype of someone you want to be like works the same way. Define your archetype very specifically, map everything that archetype stands for, and study it relentlessly.