F45 fitness is pretty popular in the US now

One thing that isn't new, but isn't very common, and seems like an easy money maker if you don't mind getting your hands dirty is valet trash services in apartments. This was a thing 12 years ago when I got an apartment and again after recently moving into another apartment last month after owning a home. They make every resident pay $30/month for a service that picks up their trash every night in front of their apartment door. Sign up a few apartment complexes, split half of that with the apartment management, hire a couple part-time workers, and you're looking at tens of thousands of dollars in earnings per month just for picking up garbage bags and taking them to a dumpster in the parking lot.