Here in Canada, because it is in short supply during the winter, we tend to think of sunlight as an unqualified blessing. In the Land of Israel, where the Mishnah was written, the relationship to the sun was different. There, the intense sunlight can bring on heatstroke or dehydration, and this reality is reflected in the first mishnah about Sukkot, which invalidates a sukkah whose sunny area is greater than its shaded area. The skakh (plant material used to make the roof of a sukkah) must provide some protection from the sun to the diners inside the sukkah.
In fact, it is not even enough if the open and covered areas at the roof level are equal. There must be enough skakh so that the floor of the sukkah is more in the shade than in the sun. Because sunlight comes through the roof at an angle and diffuses through small gaps in the skakh to a larger area on the floor, an even amount of covered and uncovered space at the roof level would not be nearly enough.
Now imagine that you are the skakh at midday. The sun is directly overhead and you are providing half-shade to the people eating lunch in the sukkah. You have met the sun halfway, but then the Earth rotates and the sun comes in at an angle. You need to spread your coverage to what seems to you to be more than halfway so that the sukkah remains valid and the people inside remain comfortable.
Life is similar. We often need to meet someone halfway and, from our perspective, it seems like we are doing so. But on the ground, or from the perspective of the other person, we are not doing enough. The metaphor of skakh reminds us, as we strive to be better people in 5779, that meeting someone halfway requires more of us than we first thought.