Display theme in page callback (without returning a value)

Hey guys,

First post here. I was wondering if anyone here could show me how to display the theme as it'd normally be displayed, but without returning a value from a page callback function

Here's an example of what I'd like to do:

function modtest_goodpage()
{
	echo 'This is content displayed on the page along with the theme.';
}

I've seen this done before, but don't know how the guy is doing it.

Any thoughts?

Thanks!