To use your analogy, when I start exploring outside the valley, I think to myself - "wow, a year ago I only knew this valley. Now I'm getting to know this new area! I've come a long way and I feel great I've made progress!".

I tend to focus on the fact I am constantly expanding my knowledge, instead of worrying about all the stuff I don't know yet.

I still consider myself a generalist, however. I can't say I'm an expert in any one area. Maybe that's why I feel the way I do.