Spiritual growth comes from consistency.

One of the atributes of Hashem is Netzach.  Hashem keeps the world running on a consistent basis. We do not have to worry if the sun is going to stop shining. We know that Hashem is consistent. One of the most important things that we have to do is to try to emulate Hashem. The Omer helps us to grow in this way because it helps us to work on the consistency of our avodah.

When we have to give an accounting of our deeds before Hashem we will be faced with the consistency of our deeds. We might explain that we did not give more Tzedakah because we did not have money, but Hashem will examine how we spent money and if it is found that we wasted money on trivial things, we will be faulted for not giving money to Tzedakah. If we are faulted for not learning, we may say that we did not have time. Then we will be held accountable for the time we wasted.

from a Shiur by Rabbi Zev Leff "The Omer and Consistency" on Aish

Our success on OA also depends on consistency. We have to weigh and measure our food every meal. We have to use the tools every day. This is the path to health.