Follow these steps to create a saved search which will show all tasks that have a due date before the current date and time:
1. Reports > Saved Searches > All Saved Searches > New
2. Select Task
3. For the Criteria add:
-Status: none of Completed
-Formula (Numeric). Set Value equal to 1 and set the Formula to: case when {enddate} < {today} then 1 else 0 end
Note: The formula is used so that time is accounted for as well as date.
To search for only the tasks of the person running the search add a criteria for Assigned To and select Mine