There are several profitable business ideas for teenagers that require minimal startup costs and can be easily managed. One such idea is social media consulting, where a teenager can use their knowledge of the latest social media platforms and language to help businesses create and maintain a social media identity. Another idea is pet-sitting or dog-walking, which can be done in the neighborhood or through a website like Rover. Teenagers who are skilled in a particular area such as music or art can offer tutoring or lessons to younger students. Additionally, starting a blog about a passion or interest can generate income through advertising and sponsored content. Other ideas include lawn care services, car washing and detailing, and creating and selling handmade crafts online. It's important to note that entrepreneurial spirit doesn't discriminate by age and anyone can start a business with a little creativity and ambition.