Have you ever been in a cave and seen a stalactite? Or a stalagmite? If not, maybe you’ve seen a valley carved out by a (relatively) slow-moving glacier. These things are formed over time. Ages, in most cases. The difference is not discernible from one day to the next, but it’s there…however small it may be.
Fitness is no different. A healthy body is a body of work, the product of thousands of decisions of varying significance.