I always thought it was because I was lazy. Going into nature seemed fall into the category of "things I never get around to". So naturally I just figured I'm too lazy to go.
It was brought to my attention that laziness isn't really a thing. I mean think about it, what stops us from doing things we want to do... Laziness to put it in physics terms is when two opposing forces hit each other, causing the object not to move. If you take equal parts excitement and anxiety you aren't going to get much done.
When that was told to me, it made me realize "ok, so what is stopping me... Why am I afraid or anxious"
In the case of out doors stuff it mainly has to do with lack of knowledge. I don't know what I'm doing or how to be particularly safe so I'mless inclined to be super adventurous, if for no other reason then I like my limbs intact. I also still consider myself a bit of clutz. I have hurt myself doing really stupid stuff before so I know it's a possibility.
So what first step did I take to getting out of the way of the fear. I bought a hiking guide book. Yes one of those travel books. But at least using that I can get an idea of what I'm walking in to before I do. And then I can be at the very least mentally prepared.
Knowledge is power and that will help aliviate the fear