Headless Rat - I shall try and give you some advice apart from really wanting to say that I think you are an idiot for the reason that you are simply just wasting away your life reaching for something which you may/may not ever find. You sound like somebody who even if you had something that made you happy, infront of you, you wouldn't realise it or appreciate it.
I don't know why you are unhappy to begin with? - You are young, you have a good education, you're a 'high achiever'. You qualified as an accountant and work for a big Company. How many people wouldn't want that? For a mid-20 person I think you have achieved very well!
Stop comparing yourself to others! So what if they have climbed mountains or ran marathons? That is their life, this is yours. If it bothers you so much, why not travel yourself? Go exploring.
The only negative aspect of your life, from what I gather is your own self. You undermine yourself - 'Professional Accountant....know very little....liability?' Have you messed up yet? How many professional people you know, who are not capable in their profession?
My advice is don't live your life saying - 'If I found what I like, I would be excellent at it and would make huge progress very fast'. I think you are deluding yourself. How many people use that as an excuse for not having opportunity?
Stop comparing and undermining, accept your life, where you are at, what you have and what it is, if you are still unhappy, only you can do something about it. The starting point is positive outlook.
Good Luck, you've tired me out now! Don't come back on with anymore life questions please!