I think people underestimate mentors. And anyone can be one if you ask someone successful in your field or in a similar field for the one or two best ways to _____. Many successful people will enjoy giving back or will be flattered that you noticed. It helps if you are younger but you can simply say you are 'young at heart'. I recently asked someone much younger for help with some social media outreach and they were surprisingly flattered I asked and shared a lot of relevant information with me. Mentors can come in all shapes and sizes.