There's an iron-clad list of things you'll need as a writer:
1) A sense of humor. Face it, some things in this business are too ironic not to be funny.
2) Thick skin. Some people will not, I repeat, not, like your work. This business is made up of people from all walks of life. That's a whole lot of differing opinions. And that is just what they are - opinions. Remember that, and take it for what it is. Don't take it personally.
3) The willingness to change your work. Be honest - if you get three or more unrelated people pointing out the same snag in your work, they might be right. You can explain your plot point all you want in person or over snail/E-mail, but you won't get that chance when someone's reading your work and you aren't around to hold their hand. Try to step back and take another look at your manuscript, and see if you can understand where your editor/agent/critique partner got stuck. The willingness to change is what makes us better writers.
4) Down time. Everyone needs a little break now and then. Spend it with your family, or go out for drinks with your critique group. Believe me, there's no restaurant livelier than one containing a table full of writers out for a good time.