Here is what traders choose to worry about (among others I am sure).  These so-called worries are usually in the form of a question and revolve around losing money:

1.  Will this trade make money?

2.  Will this trade hit a profit target?

3.  Will this trade reverse quickly against me?

4.  Will my gain turn into a loss?

5.  Will unknown news affect my trade?

6.  What if I have not done enough homework?

7.  What if my strategy is not sound?

8.  Will Cramer disagree (I had to throw this one in)?

9.  What if I get out too soon?

10.  Did I buy the right stock?

11.  What if I miss a potential move?