I'm a sceptical empiricist who believes that humans are basically sophisticated pigs mostly driven by natural impulses and socially-conditioned responses. I think at least 99% of all spiritual thinking (good example, just to show I'm not biased - Richard Dawkins' "wonder" at the complexity and "beauty" of the universe) is meaningless sophistry.
As for the application to trading, I find it works very well. Sceptical empiricism is IMO the best available approach to trading. Observe like buggery for years, cogitative to form hypotheses based on your observation/experience/intuition, test (on minimal size of course) to see how the theory holds up (markets are great for this since you can backtest *and* forward test), then implement if the theory is strongly confirmed by results. Most people's approach is the exact opposite - they form a theory based on either no observation at all, or a very superficial, cursory, and misguided quick look at the markets. Then instead of testing it they just plunge in on size (the less clueless test it naively, e.g. just by backtesting a slew of data). Then once it loses money, they become totally irrational and start trading on the basis of housewives tales or pure emotion, just like a tarot card reader's client or someone who believes in astrology. It's really hilarious to watch.
To get a good handle on sceptical/empirical thinking, go read some David Hume (Locke and Berkeley have some good insights too, and Aristotle is interesting from a historical perspective), Karl Popper, George Soros & Nassim Taleb etc. The original British empiricists laid the philosophical foundation for the scientific method and the Enlightenment, and if you look at the results of that in the progress of both scientific knowledge and civilised ethics, it is quite clear that it has proven extremely powerful. Sceptical empiricism delivers results and improves our understanding of reality - all other systems produce unclear results at best, and utter nonsense or genocide at worst. The key points of sceptical empiricism are self-doubt - something which appears lacking in almost all other belief systems, and the exact opposite of most spiritual belief systems (e.g. all the main religions); and a continual testing and refining of theories to check they correspond to reality - again, something totally at odds with most belief systems, which view such testing & refining as heresy and blasphemy.
As for "how to live", my philosophy is similar to that of Oscar Wilde - the way to conquer temptation is to yield to it. I believe that you should follow all non-destructive impulses which give you the most pleasure & satisfaction, and don't compromise your sense of personal ethics (90% of ethics is conditioned bullshit anyway) or lead to harmful excess (e.g. if you have sex 10 times a day, then your dick will hurt, you'll get fired, and your friends will probably stop calling). Basically find what really turns you on in life, and pursue that.
Pigs eat, sleep, fuck and oink whilst rolling in mud. You don't see a pig getting depressed, unless it's being fattened in some cage to make your next pork chop. Humans eat, sleep, fuck...and enjoy culture, relationships, sport, thinking, talking, and productive work. It's no different. Just learn your version of rolling in the mud - whether that involves watching WWF and drinking bud, or composing symphonies and publishing papers on Kant - and then find a way to do it as often and as enjoyably as you can. If you look at the really great thinkers, they pretty much all came to the conclusion that we know hardly anything, and that 99% of metaphysical and spiritual talk & thinking is just meaningless bullshit. The ancient greek philosophers realised it, the zen masters realised it, so did buddha and confucius. So just go out, experience some life, find out what does it for you, find out your true calling & nature, and then live that. It's the best way to approach happiness in this world.
