Throughout college, internships, and the beginning of your career, you're going to hear that you're wrong a lot. There will hardly be a week that goes by without a professor, TA, mentor, senior coworker or manager telling you that something you did wasn't quite right and needs to be fixed. Maybe your paper's introduction fell flat. Maybe your code wasn't written the way your TA thought it should be. Maybe your presentation was in the wrong colors and it was too distracting.
Whether it's a harsh reprimand or a gentle reminder, it will still happen. You might be get one of those professors that thinks tough criticism will make you stronger and doesn't cushion any of his blows with qualifiers. Or you might be lucky and get a manager that ties their critiques in with praise, saying things like "Well, this part here is really great, but maybe there's something we can do about that other part..."
You can't make everyone like everything you do on the first try, and you can't control how other people will react to your work when they think it needs revision. The only thing you can control is how you respond to their criticisms.
In the first moment, it does sting. Nobody likes to see the red pen (either figurative or literal) all over their work.
After that moment, take a breath. Your first instinct might be to get defensive. "Well, I didn't know." "You never told me you wanted it done that way."
Push away the indignation. Quell your pride. Rid yourself of excuses on why you didn't do it right the first time. It's ok, really.
Remember that in this stage of your life you are always learning. Learning means screwing things up and doing things the wrong way and then trying again until you get it right. Learning means absorbing information from the world around you and your mentors. Learning means falling down and tending to your wounds and then getting up again and making yourself stronger.
Sometimes people will be awful about giving you criticism. Sometimes they will be mean and insulting and make you feel like you can never get anything right.
Counter it with the knowledge that they are just one person, but don't dismiss their feedback. Analyze their comments objectively until you figure out the heart of the problem, looking past the needlessly harsh words to the real issue. Be honest with yourself. Ask friends and classmates about the feedback if you need to, requesting their honest and objective insight. Input from other people can help especially when you've already jumped to conclusions.
Remember that it doesn't mean that this person hates you. However harsh, an attack on your work does not mean it is an attack on you as a person.
Sometimes when you receive feedback from an exam or performance review, a single negative comment might make you feel like crawling into a hole and never coming out.
When that happens, don't listen to the voice that tells you that one comment means that you're a failure. It means you failed at one thing. But look at the millions of things you do successfully every day - you breathe, you have meaningful relationships with other people, and you probably managed to walk somewhere today without falling flat on your face. One failure does not discredit that.
Review the criticism with the person that gave it. Ask them to go into more detail if you need to, and what you can do next time. They will appreciate your initiative and willingness to get things right.
Sometimes you know you did an awful job and someone doesn't even care enough to pay attention to the fact that you did awfully. This can be just as damaging to your learning process. Every opportunity to get feedback is an opportunity to better yourself. Ask them if there was anything that could have been improved. Most of the time, they just didn't give enough thought the first time through. Asking them to take another look will get you more helpful results.
So now you have all these critiques and perhaps no idea how to begin systematically applying them. Some are easy, like including more research on a particular area in your paper or preparing for your presentation more. Some are more abstract, such as improving your coding style.
Often, we're bombarded with so many tips on how to be the perfect student, employee, friend, child, roommate, partner and person that we get overwhelmed over all the pressure to be perfect in every aspect of our lives. We're still learning in each of these areas. It takes time to improve, and each skill takes practice. Be gentle with yourself.
Remember each challenge you overcame after learning new information, remember every time that you applied the feedback that someone gave you and they were happy with the result, and remember how it feels to have succeeded in something that took forever to get right.
Remember these as you embark on new challenges and new experiences, and try to view the red pen as an opportunity to make yourself better rather than your downfall.