There's no easy answer to this one. If you're running a reasonably successful day care operation, you can decide how long you want to keep the doors open. As long as you have a ready supply of customers (who have parents with checks that don't bounce), you're probably good to go. However, you'll need a staff with a decent work ethic and an ability to pass a mandatory background check (in other words, no criminal record). You'll also need to keep your facility in good operating condition so you can comply with federal, state, and local laws requiring you to maintain a safe environment for the children.
Let's assume you've jumped through those regulatory hoops, and you're seeing a nice little net profit from your day care operation. However, you might have overlooked one small detail: you're feeling like a hamster that runs faster and faster, but can't seem to go anywhere on that maddening little wheel. You run on caffeine, you long ago abandoned your personal life, and you're starting to do Internet searches on burnout symptoms. Depending on what you find, you might be hanging on by a very short leash.