No question is stupid in QA forums.
1. Coming to your question, do you really have to run all the 20 tests at once. If not , then you can select lets say may be 5 or 10 tests from the Test set of 20 and just run those 5 or 10 tests. You can later return to run the rest of the tests.
2. But incase if you need to take a short break, i guess you can leave the manual runner on without pausing until ur MQC session times out..
3. You can also use the "End of Run" button (The red square box) to stop the manual runner instead of hitting on the Cancel button quite a no of times..