Comedian Mike Birbiglia performs his one-man show “The Old Man and the Pool” at Steppenwolf Theatre through the end of the month and he describes it as a “story that starts at my doctor’s office, for my annual checkup. I do the pulmonary test, where you blow into the tube, and I did so poorly that the doctor said, just based on that, he would think I was having a heart attack.” That sent Birbiglia down a rabbit hole of “tests and doctor’s appointments and trying to change my diet and make better life decisions and going swimming at the YMCA,” he said. “And it sort of set me on this existential…
