An Awakening From Below
We must remember that there is a tremendous difference between the mitzvos a person does on his own initiative and those he does in response to outside influences. For example, if someone lives in a community in which everyone is doing mitzvos - praying, studying Torah, building sukkos, putting mezuzos on their doorways - it is relatively easy for him to do the same. He gets a "boost" from his environment which is like "an awakening from above". But if someone lives in a non-religious environment, he has to fight against the prevailing attitudes and influences in order to do mitzvos. When he serves G-d without any special assistance from heaven or from his environment, he makes "an awakening from below" that is very precious to G-d. Every mitzva is valuable, but a mitzva motivated by such an "awakening from below" is inestimably more precious.
(Rabbi Yaakov Meir Shechter)