Sometimes the simplest thing are the things that seem the hardest. You're almost embarrassed when you finally figure it out – and realize how simple it was.
Cron jobs. Did you know you can create a script (that could technically be run if you pulled the page up in a browser) – but lets say you wanted to run this script on a regular basis. You can set up a cron job to run this php script.
So below is a screenshot of the "advanced" cron job in cpanel (your implementation may be different, but this will probably at least give you the basic idea).
Put your email address in so you'll receive the output (if you have any "feedback" printing to the screen, it will email you this output) for example. Let's say your script is supposed to download a file, and when it completes you have: echo "download was successful!!"; (you'd get an email with that text in it)
In "Command" you put:
php /home/youraccount/PATH/TO/YOUR/FILE.php
the fields for "minute" "hour" "day" etc… that will set up WHEN the script will be run. What you need to put in there so that it's appropriate for your needs (as well as additional information about cron jobs) can be found here:
faq.solutionscripts – crontab
ez-response – how cron works