Outbound Email Workflow Modify Object Pattern Usage

I am trying to set an outbound email workflow so that it changes the subject line to “Secure:” plus whatever was already in the subject line. I put a modify object rule in the outbound workflow, and set a new rule, “secure” to always true. In the True tab I have selected the activity object, and then the Subject object. If I set the type to Constant and then “Secure:” it changes it, but the original subject line is gone. I need to use the Pattern type, but I am not sure how to use it properly. All of the guides I can find just say “The pattern specified here is searched for in the body of the activity. The value immediately following the pattern, till the end of the line, is assigned as the value for the attribute”, and I can’t find any examples. Is this Javascript type regex? How would I match the entire subject line and then replace it with “Secure:” plus the original subject line? Or really the “Secure:” can come anywhere in the subject line. It doesn’t have to come first. I have tried many different regex patterns and have not been able to succeed. Any help will be greatly appreciated!