(1) Your Belief

Intrinsic Reason: This is the motivation that originates from within you, such as interest or curiosity, or perhaps you simply have a strong belief that if you do this, you'll end up being this kind of person.

Extrinsic Reasons: Essentially, you do...

• Don't be afraid to fail, but instead, use it as motivation to succeed the next time, and if you fail again, try a little harder this time.
• If we clear our minds and take the necessary action, we can become anything we desire.

You believe that people like you wouldn't act in such a manner. You obtained this pseudonym, i.e. You've just been asked to speak at a Ted Talk, but you're an introvert, so you decide not to go. Simply because you are not comfortable. You never experienced speaking in front of a group of people t...

However, you are on the right track if you adopt a growth mindset, learn from your errors, and take the necessary steps to avoid repeating them. Just be consistent and make an effort. 

In order to thrive, you must find others who share your values. Other introverts who aren't afraid to speak in front of a large group and learn from them, how they became who they are today.

There will always be urges at any moment to give up if the work you want to do is difficult. Extrinsic motivation is your enemy if the work you want to do is motivated by intrinsic factors. You decide how significant that work is.