I disagree: setting yourself up for a miserable experience might cause you to lose interest, in the case of hiking. Surely you have something else than a jeans? That's the single worst thing to wear for being active.
How would you know, though? Not jeans specifically, but there are countless gotchas with most hobbies, and for skill based hobbies you'll almost always be bad at it first.
That's essentially the advice here, get started instead of getting stuck researching and preparing.
I think preparing your mindset for setbacks and being open minded to learning from them is more practical than being overly prepared. Since you are new, you won't be able to account for all possible misery. Chalk off the easy preparation first then get out the door.
Hiking is a perfect example. Have you ever gone hiking in sneakers and jeans? It absolutely sucks. Have you ever gone camping with a shitty mattress and tent, in jeans with a way too heavy pack? It sucks and most people don't look back. If you go snorkeling with the absolute shittiest of devices and water gets into your breather, you might not want to do it again.
That's independent of the mindset your talking about. A bit of preparation can go a long way. You'll always learn, but you don't have to experience the worst of experiences to do so.
