Some people do not feel confident because they believe that they do not have enough for something special like money, good fortune, or education, or maybe your past experiences were not supportive to your actions. You should stop thinking about what you do not have. It will only make you feel dissatisfied. Instead, focus on what you have – many people do not have the qualifications/skills/talents you have.
Focus on positive things in life

Always be positive. Never let others make you feel bad or inferior. Do not engage with the people or friends who put you down. If you do not inspire confidence in yourself, others are not going to trust you. So think and speak positive about you, do not allow negativity to sit in your mind for long time. Do your best to be optimistic and talk good things to yourself and to your future.
Achieving Personal and Life Goals (Your Strengths)

If you want to know how to be more confident quickly, then focus on all your abilities, gifts, talents, passions, and strengths. Take out the pen and paper and start thinking. Because of the work you have done and the achievements you have made, you will get to know about some of its merits in advance.
Now stretch yourself. Think hard, and try to come up with something else – specifically, areas that are as yet untapped. You might not even know that you have strength in many areas until you have actually done so. And once you do, you will surely be pleasantly surprised, and this will naturally help improve your confidence.
Face Your Fears

Once you pen down all your strengths, list your deepest fears. We all have them, and these are criminals who get in the way and prevent us from taking more responsibilities and going after new opportunities.
Talk to Yourself

So next time you get a chance to do something that you are not sure about, do not be shy. Instead, say “yes” and pick it up. You already know what your fears are, and therefore when you are accepting a challenging project, you should prepare to work through them. You may not be successful in the first time. this happens. Remember, “Rome was not built in a day”. Do some analysis to find out why you failed and whether you were able to calm your fears. Learn from mistakes and keep moving forward.
There are a lot of things that you can follow to feel better. Certainly, these tips can help you to improve your confidence to some extent, lasting self-confidence comes from within, which means you need to change your self-concept to one of a truly confident person. This basically means changing your mindset and replacing your old self-concept with a new one.
Just remember to practice these things daily, in your daily actions, and work not only on building your self-confidence, but also improving yourself in general. The better person you are, the more self-assured you’ll feel.