Confidence is something that I think we've all struggled with at some point before, but there are many steps you can take to improve it. If you prefer to lead a modest life, that's completely fine - but if it's something you would like to change, then this answer is here to help you!
My confidence is all over the place. Sometimes I'll feel nothing in the world can stop me, and I'm invincible, but there are many times when I've just felt run-down and worth so much less than anyone else. This is perfectly normal, but you must learn to prevent this from causing you to suffer. Here are some top tips that are helping me improve my self-esteem:
Don't dwell on the thoughts that tell you you're incapable of doing things or any that can harm your self-esteem! These thoughts are not real; you can do anything you want to set your mind to it.
Meditation. Even doing a little ten minutes of this can relax you and somewhat lift your negative mindset. You'll be able to go back to your day with a refreshed mind, negative thoughts vacant, so long as you keep the other tips in mind.
Take risks! Each risk you take (as long as they're not blatantly ridiculous, like jumping into piranha-infested waters with four cool friends) will make you feel much more confident and better awareness of what you're truly capable of.
Don't sit on your ass, scrolling through social media for hours. Recently I've stopped this and have been so much more inspired. Get up, do something you enjoy, maybe go and socialize, and love yourself!! Social media can give you unrealistic expectations of the way you should be. No one is perfect.
Take pride in your appearance. Make sure you don't go too long without a shower or a wash, it's always nice to smell and feel fresh. Maybe you could have a pamper night, where you focus solely on relaxing and taking care of yourself. It's always lovely to look and feel physically good.
Don't compare yourself to others. It's an extremely unhealthy habit with no beneficial outcomes. You'll end up feeling miserable and with your self-esteem drained. If there's a situation you're tempted to rebuke yourself, focus on your achievements instead of what you should have done better. There's no changing the past, just think 'at least I'll know for the future'! :)
Make new friends! It is perhaps easier for teenagers like me, but joining clubs outside of school that you're interested in can be so beneficial. You might find some of your favorite people along the way, too - you never know.
Rant to friends/people who give helpful advice! Just speaking and letting your thoughts and emotions flow can be beneficial. Whenever I'm in an awful mood, I find that talking to kind people who will empathize and give me good feedback really relieves stress, and I can focus on my confidence much more clearly.
Find someone whose spirit you aspire to have, and copy them. Not in the sense that you copy every word they say, but just take note of their actions and how they start conversations with people, etc. I found this extremely helpful - it's like they're your guide. Make sure they're not cocky, though, just outgoing and kind.
Put yourself out of your comfort zone in good ways, like skydiving or bungee jumping from extreme heights or something crazy like that! Never tell yourself you can't do things. If you're a teenager, then just don't be scared to be your true self or to talk to people. I've always been very extroverted and can assure you, and you feel terrific after perking up all your courage to speak to new people and make new friends. It's exhilarating. You'll never get anything if you don't take any chances :D I hope you found this useful!
Thank you for all of your support, every one of you is so incredibly talented, and you are incredibly loved. I hope you're doing well.
Some bonus point to note:
1) Don't care about what people think of you. The most confident people give zero shits about how others perceive them. They have an objective and will plow through whatever or whoever stands in their way.
2) Look people in their eyes. When you stare at someone, sustain eye contact. It might be weird at first, but you will get used to it. Eye contact is usually an indicator of dominance. The most powerful, influential people have eyes like a hawk.
3) Study body language. There are dozens of books out there on body language. Read up on them to learn how to read and understand a person's behavior better. That way, you can learn how to implement proper body gestures to appear more confident.
4) Don't hold back any thoughts. When there is something you don't agree with, say it! You will appear more confident because you are not afraid to abstain from your true feelings. If you think something is shit, tell it how it is. Don't hold back on what you typically believe in.
5) Express yourself. Dress how you want to dress. Listen to music you want to listen to. Say what you want to say. Don't be terrified of expressing yourself. People judge anyways, regardless if you're elegantly dressed or dressed like a star on bum fights. Many are scared to express themselves and typically endure living a life they don't want to live.
6) Find a passion. Find something you love! Something that you wouldn't give up for an incomprehensible amount of money. Passionate people are always confident; they believe in their passions regardless of other's judgments.
7) Exercise and eat healthy. Trust me on this one. Your body and mind are compatible with synchronized. If you eat like shit, you will feel like shit. Workout every other day. Set reachable goals with your body. Once you start seeing results, the rush is unimaginable. You will want to exercise and eat healthily consistently.
8) Don't be afraid of NO! You will fail countless times. You will get rejected numerous times. Like rocky always said, "it's not about how hard you hit, but how many times you get hit and keep getting back up." NO scares many people. It prevents them from accomplishing their aspirations and goals. If you let NO stop you, you're better off just giving up. Learn to love that word.
9) Read. Reading will improve many aspects of your life, including confidence. The more you read, the more knowledge you will accrue. You will become an informative person. You won't seem stupid and oblivious. Instead, you will be informed and knowledgable.