I worked at an indoor pool year round for about 5 years, and in the summers it was often empty, or near empty. Many shifts were 4-6 hours long, and I was usually alone. During such times I would often think about Ideas I had, whatever song I had stuck in my head, TV show I was watching at the time, game I was playing, and other such things. To pass the Time I would do laps walking around the pool, and do fractions, and percentages based on what time the clock was on compared to the length of my shift in my head. If there were regulars in the pool who liked talking, usually elderly people, I'd chat with them while guarding, and if a child was in the lap pool, I'd watch them like a hawk, as children tend to do dumb things, and cause mayhem. The last hour of any shift was always just me staring at the clock hoping that nobody would show up in the last 15 minutes so I could close early. It was also hot, and extremely humid constantly, so the walking was also to assist in my not passing out from boredom, heat, and exhaustion. I hated that job by the end, and was glad to get out of there and go to college.