Younger managers are becoming more common, especially with advancing technology. As the younger generation has grown up with technology, they quickly gain experience in certain areas and may be more suited to lead a project than those who are older but less familiar with the technology. Even if your new boss is less experienced than you in some areas, it's important to be respectful of his/her knowledge and skills. They've earned their position and should be treated as a professional.
Try to avoid drawing attention to the age difference. Don't preface a statement with 'when I was your age', 'back in my day', 'we used to do things this way…', on so on. On the other hand, you also shouldn't try to act younger and more 'cool'. There's no need to learn the latest slang or feign interest in pop culture. Just be yourself and do your job well.
Stay confident in your own abilities. Some people are embarrassed to be in a lower position than someone younger. They may feel that they deserve the position instead or they may feel ashamed for not accomplishing more at this stage in their career. It's better to focus on what you're skilled at and what you can contribute to the team.
No matter what your age, always be willing to learn something new. Stay up to date on the latest technology in your field, read current articles, and try new methods. When you're unsure of something, don't be afraid to ask questions. Your younger boss and colleagues should also be open to learning from you. Even if you may be less experienced in the industry, you have valuable wisdom to offer from your life experience. Mutual respect is key.
Be respectful and professional
Don't draw attention to the age difference
Be confident in your own abilities
Always be willing to learn