This quote means that it is not useful to measure the success of each day only by its results or output. Instead, you should be focusing on the small steps you are taking now which will help give you a larger payoff in the future. It is important to remember that planting a seed can take time to grow and bear fruit, and so it is not always clear what impact or success we have had in one particular day. However, if we persist in planting good seeds, then eventually we will reap a good harvest.