I agree with Hankster; get to know yourself better and your worth/self-worth. When they joke about what the cat dragged in, grin and agree with them; if you agree with people, they have nothing to keep going with (complaints, teasing, negative comments etc.).

Make sure you know the chain of command; I can't believe just anyone can give you things to do/their work. Don't focus on what they are doing, what they are probably getting paid, etc., just do what you want to do (if you don't like the work you should not be working there) in your way for your reasons -- you do have a plan for your career/life don't you?