how to build the parallel nature into the script?

[paralleluser]

Dear Friends,

Given a shell script, script.bash, it takes one argument, $1, which is a file 
name to process, like this:
script.bash myfile.txt

To parallelize this I can do:
parallel script.bash ::: *.txt

But what is the easiest way to build the parallel nature into the script so I 
can do:
script.bash *.txt

and parallel does its magic behind the scenes?

Thanks!...