How to Show Maturity
The best way to show maturity is to follow through on commitments you make, since that will let people know you are someone they can rely on. For example, if you promised a friend you'd go to their recital, be sure to go, or if you promised your parents you'd tidy your room, do it without being asked. You can also show your maturity by letting others help you learn important life skills, like saving money. For instance, if you're not sure how to save, go to someone you trust and ask for their advice. You might say: “Uncle Thrifty, can you help me decide where to invest my money?”. Once you've got their advice, remember it for the next time you have to decide for yourself.
Live by your values. Maturity includes making decisions based off of your values, ethics, and morals, instead of what feels good in the moment. While spur-of-the-moment decisions can be fun, weigh whether there are any long-term consequences. Allow your values to guide your life. Let your character master your desires. Reflect on people you admire and what values they embody. If it's an athlete, maybe you admire hard work, dedication, and pushing the body to the limits. If you admire a spiritual leader, you may admire the commitment to honesty and compassion. Reflecting on positive traits of others can help you discover your values. Whatever you choose, commit to it. Show people that you are willing to live out your values, even if it presents minor inconveniences to you. Honor your feelings. Maturity includes emotional development. Unfortunately, people (and especially teens) get feedback that tells them to ignore feelings or to devalue them. Some examples include holding back tears, apologizing for crying, or saying “I'm fine” when you are hurting inside. It's healthy to express your feelings and to really feel them. We are wired to have feelings, and expressing them is a loving acknowledgment of the beauty and struggle of life.  Show maturity by articulating your feelings. When feeling sad, take a moment to check in with your feelings. Reflect on what may be making you feel sad, such as a fight with a friend or parent, a low grade, a pet that has run away, or being away from a parent for a weekend. Instead of ignoring the feeling, feel it fully and recognize that it's important to acknowledge all of your feelings, even when they are painful. When expressing your feelings, start by saying “I feel…” and avoid saying “You make me feel...” Notice the difference between “I feel sad” and “You make me feel sad.” One accuses someone and the other expresses the self. Expressing your feelings allows you to empower yourself. It's not an opportunity to make accusations. Once you've acknowledged your feelings, start working through them. For example, you can tell yourself, "It's not fun to feel sad, but I know that feelings don't last. I'll feel better soon and I'll find a way to work out what I'm feeling." You can also remind yourself that feelings aren't facts: for example, just because you feel "stupid" one day does not mean that you are. Be generous with yourself as you work through your feelings. Be teachable. It might be fun to feel like you have all the answers and you don't need anyone's input, but maturity includes being open to the knowledge and wisdom of others. It's okay to admit you don't know everything (nobody does!). People around you have wisdom that you may not, so seek out the wisdom of others before making big decisions. This shows that you are willing to learn from others. When faced with an important decision, seek input from people you trust, like a teacher, coach, spiritual leader, parent, grandparent, aunt or uncle, best friend, or other trusted adult or friend. Remember that no one can make decisions for you. While others can be helpful (or not), your decisions are ultimately yours to make and nobody else's. Maintain a non-judgmental attitude. We all love that friend that is always supportive, never gossips, and we feel like we can tell anything to, even if it's embarrassing. Being non-judgmental means having an attitude of acceptance, understanding, and acting authentically. Accept the people in your life as they are (including yourself!). Don't demand changes. Don't put yourself on moral higher ground, but show others that you can learn to accept everyone in your life through understanding. Nobody is higher or lower than you are. Learn to withhold your judgments and approach people through compassion. Judgments are ways to create distance between yourself and someone else. Use empathy and “walk a mile in her shoes” and discover that regardless of how flawless someone's life appears, she has problems that cause her pain, too. Gossip is one way to spread judgment about someone. Be careful what you say when you talk about people. If someone starts to gossip, you can say, “That sounds like gossip, and I'd rather not hurt anyone's feelings. I'd rather talk about cats.” Keep your commitments. When you were younger, your schedule was made for you: you went to school or sports or dance. Now, you may have more ability to make your own schedule. When you say you will do something, do it. Even if it isn't your idea of fun, show people that they can count on you and that you are reliable. When you tell someone “yes”, honor your commitment. Show people that you can be trusted. Treat people with respect. Treat those around you with respect, with both your actions and your words. Respect builds trust and support in a relationship, whether it be with your parents, siblings, friends, or romantic partner. A good way to learn respect is to first treat yourself with respect. Don't feel pressure to do anything just because everyone else is doing it, but respect your mind, body, and spirituality enough to listen if one of them is telling you not to participate. Learn what it feels like to respect yourself, and make sure you treat others with the same respect. Say “please” and “thank you” often. Even if you're in an argument, refrain from name-calling. You can disagree with someone while still being respectful. Think before you speak and hold off from saying anything that can be hurtful. Say, “I appreciate and respect your opinion, even though it differs from mine.” Treating other people respectfully shows maturity in how you interact. Act calmly in conflict. It may be easy to retaliate when in an argument and unleash your anger, but keep your cool. Keeping calm in stressful situations has positive long-term health benefits, such as less inflammation in the body. Being calm and thinking about something positive can help when stressful events occur. By not raging but choosing to keep calm, you show others that you are able to handle your emotions in a mature way. When you feel anger coming on, take a couple deep breaths and connect with your body. Feel where the anger comes from and listen to what it is telling you. Allow your rational mind to determine how you want to handle the situation. If you struggle to respond calmly, ask for a time out. Say, “This is important and we need to talk about it, but I am so angry and I need to cool down. Can we talk about this after I've had some time to think?” Avoid being defensive. When things get heated, resist the urge to defend your views. Don't be a brick wall, but be intentional to listen to other people's opinions, even if you fiercely disagree with them. There are no two people on the planet that will agree on everything. Be respectful and listen, just as much as you want the other person to listen to you. Listening to what other people have to say and not acting defensively shows that you are mature enough to handle conflicts. You may disagree on clothes, texting, boys/girls, or friends with your parents and you may not find common ground. If you want your parents to understand you, make sure you understand them, too. If you feel defensive, don't fight back, but speak your feelings. Instead of saying, “You're calling me a liar! I'm not a liar!”, say, “It's important that people are truthful with me, which is why I'm hurt that it feels like I'm being accused of lying.” Own your shortcomings. Don't blame other people for the problems in your life. Recognize that you have choices in how you act and react. All relationships are interactional, meaning that you both contribute to how you feel and what happens. It's much easier to blame people for how bad you feel, but recognize your role, and take responsibility for your actions. Reflect on what actions you took that contributed to the situation, and own up to them. Even if someone does have shortcomings, it doesn't mean that you can blame her for your problems or how you feel, or treat them as less than you. If you've let somebody down, let them know. Instead of blaming external things, say, “I'm sorry I didn't show up on time. That was my fault and I didn't allow enough time.” Plan for how you'll do things differently in the future: "Next time, I'll leave ten minutes earlier so I can get there on time." By owning your own mistakes, you show others that you are humble and can admit fault, a very mature action. Make requests. When you want something, don't be demanding. Imagine how you would react if someone was always demanding things of you: you probably would not like it. Instead, make requests. Make your case and then explain your request. It's the toddler in the shopping cart that yells at her mommy to buy the chips. You're better than that. If you want a dog, don't whine until you get one. Ask your parents for a dog, and show that you will take responsibility for it by walking, feeding, and taking care of it. Show your maturity by making a request and following through with actions. Instead of saying, “I deserve it!” or “Why aren't you giving me what I want?”, say “I would like to tell you that I really want something, and I would like you to hear me out.” 
Live by your values. Honor your feelings. Be teachable. Maintain a non-judgmental attitude. Keep your commitments. Treat people with respect. Act calmly in conflict. Avoid being defensive. Own your shortcomings. Make requests. 