Mentoring is such a hard and difficult facet of life. You want to pay it forward, you want to help someone grow, you want the best for them. I can only imagine this feeling is what having kids must be like, only much less intense. I agonize over the idea that my thoughts, my actions, actually influence someone. If that's the case, I must spend as much energy as possible to make sure I'm doing something great so the people who look up to me actually have something worth while to learn.
After much thought and discussion, I think I've finally managed to figure out a mentoring philosophy. Not a teaching one, but a mentoring one: install good defaults. We think about this all the time in computer science. Secure by default. Fast by default. Why don't we have the same concept when it comes to people? I think we do, just society calls it something different: values and morals.
When people grow up, when you analyze different cultures, you see different cultures optimize and cultivate different values and morals. It's how people act by default. For example, the default action in a restaurant in Europe seems to be take your time, enjoy the table wine, enjoy the food. If you are in a rush, you have to actively override social norms to do it, it's "rude". The momentum behind the idea of enjoying your meals is so strong that most people do it.
In asian cultures, the default is to value education almost more than anything else for the kids. That's why you see across the board, asian kids generally do better in every test compared to other cultures. It's valued so much that it becomes the default thing to do. If the running default theory in your family is that you will go to college, you most likely will. It takes an inordinate amount of effort to stand up to your parents, culture, and gut to say no.
Morals are another way society tries to teach people because it instills a default. Most people, thankfully, are appalled at the idea of killing someone. Whenever something is morally appalling, eg selling drugs (I don't find this morally bad, I'm just saying society does), it takes a concious effort to do it. Not only that, your initial reaction is to not sell drugs, which makes you very aware of what you're doing.
As a mentor, that's really what you're shooting for. You want to install great defaults for your mentees. The default reaction when something sucks is to recognize that it sucks and makes it better. The default action is to always be kind to other people. The default is to write clean code. It should take an inordinate amount of energy for someone to settle and say their work is good enough.
Other people allude to this property, it just never clicked as a mentor. There's an old Hindu saying "For the first 30 years of your life, you make your habits. For the last 30 years of your life, your habits make you". It's the same idea - instill great habits and great things will happen as an offshoot.