The golden rule of lawn care is to mow no more than 1/3 off the top of the grass blade. The reason is that to cut more puts undue stress on the plant and makes it susceptible to scorching from the sun. Grass grows faster in the summertime, which means if you're not resetting your mower blade, you're probably chopping way too much off the top. Raise the height of your blade based on the height of the lawn for healthier grass. You may need to adjust it more than once this season to get the best results.