http://www.inc.com/author/geoffrey-james
Research has shown that successful entrepreneurs are supremely self-confident. However, contrary to popular belief, self-confidence isn't in your DNA. Like every other life skill, it's something you can learn and cultivate.
Based on an excellent post by my friend Shyam Ramanathan, here are some great ways to build unstoppable self-confidence:

1. Record your accomplishments.

Starting from your earliest memories, list out every achievement you've experienced so far. Include positive experiences (learning a language, winning a competition, etc.) and times you've overcome obstacles (like surviving a family crisis, enduring an illness, etc.).

2. Keep a victory log.

Add to your list of accomplishments as you achieve victories both large and small in your career and personal life. Tracking and reviewing your accomplishments creates and reinforces your self-image as a winner, with a consequent boost in self-confidence.

3. Map out your strengths.

List out your strengths (self-discipline, honesty, friendliness, courage etc.) Knowing your strengths helps you apply those strengths in day-to-day situations, creating more victories and increasing your self-confidence.

4. Reframe your weaknesses.

List your perceived weaknesses (procrastinating, impatience, etc.). Beside each, write the corresponding benefit. For example, "impatience" becomes "pro-active." Add the benefits to your list of strengths. Crumple up your "weakness" list and throw it in the trash.

5. Deepen your motivation.

Revisit your goals and deepen their emotional draw. For each goal ask "why do I want this?" and "how will I feel when I achieve this?" The stronger you visualize the emotional rewards, the more motivated you'll feel, thereby creating more self-confidence.

6. Confirm your tactical plan.

Knowing that you've got a good plan to achieve your goals creates more self-confidence in your ability to reach them. Eliminate activities that don't serve your goals and increase your activities that move you forward. More momentum equals more self-confidence.

7. Find the best mentors.

As Ramantathan points out, "with the internet, you can get access to the masters in your field much easier than at any point in history. Read their blogs, listen to their podcasts, document what you have learnt and share it with your network."

8. Read the self-confidence classics.

Read (or reread) The Seven Habits of Highly Effective People, How to Win Friends and Influence people, The Magic of Thinking BIG, As a Man Thinketh, and Think and Grow Rich. Incorporate their ideas with the confident knowledge they've worked for millions.

9. Admit your own ignorance.

When you encounter situations where you don't know the answers, resist the urge to bullsh*t your way out. Admitting what you don't know reaffirms what you truly do know, creating a firm foundation for realistic self-confidence.

10. Associate with confident people.

Self-confidence is contagious, so find multiple opportunities to spend time with people who believe in themselves and their abilities. If you must spend time with the timid and tentative, be a good role model. Pull them up to your level; don't let them bring you down.

11. Appreciate being envied.

Make no mistake about it, when you're self-confident you're going to attract the envy of those who aren't. Rather than wilt under the disapproval, take their inevitable envy as a sure sign that you're on the right track.

12. Collect quotes on self-confidence.

Keep a running list of every quote you hear about the value of self-confidence. Here's a great quote to get you started: "If one advances confidently in the direction of his dreams and endeavors to live the life he has imagined, he will meet with a success unexpected."