You need will.
You need the desire.
You need the determination to go on -- even after you've scorched the first batch of stew, burned the sauce, mutilated the fish fillet, and lopped off a hunk of fingertip.
You need persistence, the ability to understand that with every mistake comes valuable information. I'll tell you what i tell every rookie cook in my kitchen, after he ruins a perfectly good consommé: "Throw it out. Start over. Do you understand what you did wrong? Good. Now don't do it again." Know that you can read about breaking a butter sauce all you like; until you've actually broken it -- just when you needed it -- you won't understand it on a instinctive, cellular level. Screwups are good. Screwups -- and bouncing back from screwups -- help you conquer fear. And that's very important. Because some dishes know when you're afraid. They sense it, like horses, and will -- as my friend Fergus Henderson will tell you -- "misbehave."
Eventually, your hands, your palate, even your ears will learn, they will know when things are going right, and will sense in advance when things are in danger of going wrong.
Do not be afraid.
You will need a pure heart, and a soul, meaning you are cooking for the right reasons.
You don't collect and cook recipes, or compile dining experiences, like a butterfly collector. You must enjoy what you are doing. If there is any real sin in the culinary universe, it is the sin of snobbery. If you're afraid of a little grease on your chin or of eating with your hands, are squeamish about bones, fish heads, and guts, are ambivalent about garlic, are too precious with your food, then put this book down now (you probably didn't get any food on it yet) and return it. It's not for you. Buy another cookbook. One with lots of purty pictures.
You need passion, curiosity, a full spectrum of appetites. You need to yearn for things.
Chefs' appetites and enthusiasms, you may have noticed, rarely end with food. I am deeply suspicious of any cook who is less than enthusiastic about sex, music, movies, travel -- and LIFE. A few years back, dining with friends at one of the "best" restaurants in the country, we sat back, after many courses of lovely but sterile, artfully arranged plates of food, curiously unsatisfied. I wondered aloud what was wrong. On of my companions suggested that the chef "cooked like someone who's never been properly fucked in his life."
You need love.
Hopefully it's love for the people you're cooking for, because the greatest and most memorable meals are as much about who you are with as they are about what you ate. But love for what you're doing, and for the ingredients you're doing it with, will more that suffice. I suggested once to a maniacal barbecue professional that cooking well was not a profession, it was a calling. He laughed and went further: :It's an illness." I knew just what he meant. You must like cooking for other people, even if you neither know or like them. You must enjoy the fact that you are nourishing them, pleasing them, giving them the best you've got.
You must ultimately respect your ingredients, however lowly they might be. Just as you must respect your guests, however witless and unappreciative they might be. Ultimately, you are cooking for yourself.
Anthony Bourdain, from the introduction to Les Halles Cookbook: Strategies, Recipes, and Techniques of Classic Bistro Cooking