A beautiful lawn requires more than just regular mowing and watering to be healthy. It requires rich nutrients from fertilizer applications to stay green and lush, along with careful weed control applications with herbicides to control and protect against unwanted weeds.
While some homeowners opt to tackle this themselves, off-the-shelf products contain heavy fillers that can actually do more harm then good. That, in combination with lack of expertise and time, usually results in a less than desired result.