Low hanging fruit is a metaphor for easily obtainable results. When you picture this, I think of apple trees heavy with fruits and some are easy to reach. When you pick those apples, the branches become less heavy and as a result the higher up apples get out of reach. Picking the low hanging fruit means that the other results get out of reach as a consequence.
When you look at modern orchards, you see something different. The trees are no longer allowed to grow tall. All fruit have become low hanging fruit. Consequently, when you plan on some activity, and you do it in the classical way you may find low hanging fruit. When you find a way to think outside of the box, make this paradigm shift, you may have only low hanging fruit.