There is an important aspect to being a professional that is necessary to learn, but difficult to teach. While not just true for professionals, it is especially true for anyone in a professional setting to set ego aside and keep oneself humble.
Everyone has limits. No matter how experienced or talented you may be, there is always someone who knows something you do not or can do something you cannot. This should be viewed not as personal shortcoming, and certainly not as a danger to your value in the company, but as a reminder that there's room for you to grow.
Don't compare yourself to others. No value will come from this. The person sitting next to you at work may be a wizard with object-oriented languages, but struggle with functional programming. If you are in the opposite position, the two of you have an opportunity to learn from and teach one another. Everyone wins!
Never be afraid to make mistakes. Being afraid to make mistakes keeps you afraid to risk success. Everyone messes up at one time or another. Mistakes build experience, which helps to diminish the effects of future mistakes. The humble developer will recognize that he or she is not perfect. Mistakes will happen. Own them as they occur; they are invaluable opportunities to grow. Don't hide from them; and certainly don't hide them from others.
Keep yourself open to the input of others. There will be times when you think you have the best idea or solution to a problem. If you're on a team, or if you're even the slightest bit uncertain, allow for the suggestions of those around you. Being surrounded by like-minded people doesn't mean that you all think the same way. Everyone has a different perspective. All it takes is one good suggestion to toss your idea from debate. This isn't a bad thing; it's fantastic!
You may find yourself working diligently on a project, tackling challenging problems and bringing a lot of value to the company. The team meeting might come up without the slightest mention of how hard you worked or how much you contributed. For some, this hurts. Personally, I've experienced this feeling more times than I care to remember. However, there's something important to keep in mind. Recognition isn't always announced. Just because you weren't publicly thanked for your efforts doesn't mean they went unnoticed.
Your employer and your team will recognize your skills and contributions, even if you never hear about it. As satisfying as that would be, you should instead focus on the rewards of the roles you perform. Let yourself feel great about the things you achieve. Share your enthusiasm over team successes. Acknowledge the achievements of others. Let them know that they are appreciated - that they are valued team members. These acts can be as satisfying as being on the receiving end of them.
Recognition is easily given, difficult to earn, and often arrives unexpectedly.
Always be willing to help. No man is an island. Everyone relies on those around them, especially developers. You will find yourself seeking the advice and aid of others from time to time. This is more than just expected; it is encouraged. It is the core of the learning process. As you learn and grow, you will find yourself being asked for help. Do more than just make yourself available; share your knowledge and experience wherever it may help others.
"We're all in this together."
For all our faults, we are collectively a team. We make mistakes together. We overcome challenges together. We recognize each other's unique abilities and encourage perpetual growth in each other. We seek help when we need it, and give back whenever we are able.