My son (5 years old) is going in tomorrow for his 5th attempt at a sweat test. Is there anything I can do to increase the odds of him sweating? All four times, they didn't even get a drop! I've been making sure he is very very hydrated all day, and he'll be drinking a whole lot before the test tomorrow, too. But are there any tips that you've heard of to try to make sure we don't have to do this a 6th time? Any advice would be greatly appreciated...Thank you!!