Rabbi Kook teaches that even mere contemplations of t'shuva have significant value.
There are things, however, that have an absolute value, regardless of their tangible impact in this world. Truth is an example. Holiness is another. To this list, Rabbi Kook adds good thoughts. Contemplations of t'shuva, even if they do not lead to a resulting change in behavior, bring benefit to the individual and the world.
This is similar to the question in the Talmud - which is greater, Torah study or good deeds? The answer is Torah study because it leads to good deeds (Kiddushin 40B). You might think that if the ultimate goal is the deeds, then they would be more important. But our Sages tell us that the thought processes which lead to the deeds is of primary concern. Being immersed in Torah has an absolute value in itself.
"The thought of t'shuva transforms all transgressions and the darkness they cause, along with their spiritual bitterness and stains, into visions of joy and comfort, for it is through these contemplations that a person is filled with a deep feeling of hatred for evil, and the love of goodness is increased within him with a powerful force" (Orot HaT'shuva, 7:1).
T'shuva can be dissected into two different realms. There is the nitty-gritty t'shuva of mending an actual deed, and there is the thought process which precedes the action. The value of these thoughts is not to be measured according to the activities which they inspire. For instance, a person may decide that he wants to be righteous. But when the person tries to translate this thought into action, he finds himself overwhelmed. To be righteous, he has to get up early in the morning to pray. He has to stop doing a host of forbidden deeds. He has to watch what he says, watch what he sees, and watch what he eats. Before he even begins, his will is broken. Though his wish to do t'shuva was sincere, he couldn't find the inner strength to actualize his thoughts into deeds.
Rabbi Kook says that all is not lost. This person's original idea to do t'shuva stemmed from the deepest recesses of the soul, where it was inspired by the spiritual waves of t'shuva which encircle the world. Thus he has already been touched by t'shuva's cleansing streams. In effect, he has boarded the boat. Though his willpower may be weak at the moment, his soul is longing for G-d.