Yes, worrying involves stress and accomplishes nothing.
Best to not worry.
Michael Dell* would disagree with you.
I read where he suggested that the only thing that kept his company so
successful was worrying. He said that he is constantly fearful of advances
in other companies, and it pushes him to continuously strive to better his
own products at a faster rate than his competition.
*It may have actually been an interview with Steve Jobs.