They used to be performed regularly on people as they got older but not as much anymore. They are expensive to do and they don't always give accurate results. There are sometimes false positives. People were being diagnosed with heart problems when the problems weren't there. Further tests are now done to confirm a diagnosis like a nuclear test or cardiac catheterization.
Treadmill stress tests are nothing to worry about, the risks are low. The test is not designed to test for something like a VO2 max which athletes take. That test is designed to take you to the very edge of what your body can achieve. The test for regular patients is just to get your heart beating that little bit quicker to analyze how your heart performs under stress including blood pressure.
So the test will determine how well your heart pumps blood as it will need to feed the muscles with oxygen used during the test. As said before, a physician is always with you so the test is safe. It's designed to stress your body not take to the edge of peak physical fitness. You will be asked not to eat a big meal 2 to 3 hours before.
You need to not use moisturizer on your chest for that day otherwise the electrocardiogram pads won't stick while your performing the test. These are essential to measure the signals from your heart. Sometimes the physician might have you breathing through a tube to test your lung capacity and see how well you recover. In conclusion a stress test is nothing to worry about and you'll be ok.