How to loop only through files that don't exist in destination using an SSIS package?

Question

I have a folder on the network with files and I'm moving the files from one folder to another folder. But I only want to move new files, so only copy over files that do not exist in the destination folder. How? I already have the for each loop container and a file system task. I'm using variables. Right now it copies all files from one folder to the next everytime the package is executed. Is there some sort of conditional tool that I can stick in there? I'm not really good at writing scripts so if that is the only solution I may need your help.