To me, Beginners Mind is about having a fresh and direct perception of my experience. Still having the benefit of expertise and experience, but at the same time having a direct and unclouded view of the present, as if I was a beginner all over again.
As we age, we gain valuable experience and knowledge but how much of this can actually hinder us? Experience can become a thick lens through which we see things. In some situations this can be a real strength, but in others it can hold us back and delude us without us even realizing it.
Like the man with the hammer, who only sees nails. He impresses everyone while hitting nails, until he starts hitting things which he shouldn't. He has no idea what the problem is. Habitually acting entirely from his experience, the hammer is always his solution to everything.
This is what it means to be "stuck in our ways", always habitually applying the same solution derived from our experience, even if the situation is actually a completely new one with a different optimal solution. I'm sure we can all point to a parent or elder who is like this. We may think that "I will never be like that when I'm older", but the truth is, we are all destined to become stuck in our ways eventually unless we cultivate our ability to see things freshly, free from the fetters of our own knowledge and experience.
These days we are trained to put excessive value in experience and learned information. There is less value in the deep skill of seeing things very clearly and directly, which can erode away in us over time, just like our youth.
I myself have experienced feeling younger as I get older, by developing the skill of seeing the world through fresh eyes again and again, through meditation and mindfulness. It essentially the unlearning of piled-up mental habits. It is truly a kind of fountain of youth!
Of course past experience is not just thrown away, only the automatic mental habit of seeing through it all the time. Experience is still a powerful tool. A direct perception of reality gives us immense freedom in any moment by allowing us to see a larger number of possibilities, much like an imaginative child. And yet with experience as a tool in our back pocket we can still choose a wiser option than a child.
We benefit from taking a pause and choosing our tools wisely, with fresh clarity, rather than habitually. Be open to picking up new tools. Otherwise you might end up being the one hitting everything with a hammer!