How do I list only the custom tasks in a Gradle build file?

I have written a gradle build file which several custom tasks. They are all like the following:

task runThis(type:JavaExec) {
    doSomething()
}

When I enter "gradle tasks" in a terminal, none of the tasks I have written myself are listed. Only the standard list of tasks which appear when I run this command against a new project.

How do I get the tasks to be listed? And is it possible to print ONLY the custom written tasks?