Gemara on Amud Beis tells us from a derasha, that one who eats on the day before Yom Kippur is given credit as if he fasted for two days, instead of one.  Rashi explains that by eating with the intent to prepare yourself to properly fast the next day, your eating today counts like fasting.

From here we see a wonderful Torah principle, that the intention of our good actions can bring merit even in mundane tasks. Thus, eating on erev Yom Kippur with the intention that one could be of sound mind and body on Yom Kippur, counts already as fasting, even though you are enjoying eating.  

We discussed in detail on Daf 68 this principle based on the Mishna (Avos 2:12), “Let all your actions be for [the sake of] the name of heaven.”  And in chapter 5 of the Shemoneh Perakim, the Rambam states that every act, from the simplest physical act such as eating or sleeping, to the most spiritual should be with the intent of knowing God and growing closer to God. 

Similarly, Rambam in Hilchos Deos (3:2):

It is necessary for man to set his heart and all his efforts solely to know the Name, blessed is He! so that his sitting down, his rising up and his speech shall be facing this goal. How may he accomplish it? When he will buy, or sell, or do work for wages, he should not have in his heart the accumulation of money only but he should perform these duties as a means to acquire the necessities of the body, as food, drink, dwelling-place and marriage; likewise when he will eat, drink, or lead a family life, he should not set his heart upon these things for the sole enjoyment thereof, until, as a consequence he will not eat and drink save that which is sweet to the palate, and marry to gratify his sensuality only. But he shall set his heart to eat and drink solely in order to keep his body and limbs in good health.

And he states further in the beginning of chapter four of Hilchos Deos:

It is impossible that one should understand or know aught of the divine knowledge concerning the Creator when he is sick. Therefore, the maintenance of the body in a healthy and sound condition is a God-chosen way. It is necessary for man to distance himself from things which destroy the body, and accustom himself in things which are healthful and life-imparting.

To my knowledge, no one uses this Gemara about Yom Kippur as a support to this idea.  So I am proud to say, you heard it here first, at Psychology of the Daf.