The Mishnah in Avot [1’ 3’] declares “Do not serve G-d for the sake of reward”. This is codified in the Rambam [Laws of Repentance, Chapt. 10. Halachah 1.]:
“...A person should not say: "I will fulfill the mitzvot of the Torah and occupy myself in its wisdom in order to receive all the blessings which are contained within it or in order to merit the life of the world to come."
"[Similarly,] I will separate myself from all the sins which the Torah warned against so that I will be saved from all the curses contained in the Torah or so that [my soul] will not be cut off from the life of the world to come…”.
While one should certainly seek to inspire those who have not yet chosen to live committed Torah life, and teach about the great value that awaits in the World to Come, that is not the ultimate goal in Judaism. Rather, the Rambam writes [ad. Loc.]:
“...One who serves [God] out of love occupies himself in the Torah and the mitzvot and walks in the paths of wisdom for no ulterior motive: not because of fear that evil will occur, nor in order to acquire benefit. Rather, he does what is true because it is true, and ultimately, good will come because of it.
This is a very high level which is not merited by every wise man. It is the level of our Patriarch, Abraham, whom God described as, "he who loved Me," for his service was only motivated by love…”.
With this background in mind, the Rambam’s comments in Chapt. 7 Halachah 1 [Laws of Repentance] are all the more remarkable. Rambam writes:
“Since free choice is granted to all men as explained, a person should always strive to do Teshuvah and to confess verbally for his sins, striving to cleanse his hands from sin in order that he may die as a Baal-Teshuvah and merit the life of the world to come…”.
Here, the Rambam elucidates clearly that the primary intent of one engaging in the Mitzvah of Teshuvah [repentance] is to earn eternal reward. This should be a direct violation of the ideal of the Mishnah in Avot mentioned initially!
The Sefer Mazkeret Menachem, which can be found in the back of many of the popular editions of the Rambam, offers, that the Mitzvah of Teshuvah is an exception to the above concept. Teshuvah-repentance-is communicated in the Torah with the command “You shall choose life.” The Torah is clearly referring to the choices that one should make that will result in the earning of eternal life in the world to come; the Torah is obviously not commanding one to choose to be alive! Hence, the Torah communicates that one should do Teshuvah for the sake of earning eternal reward! Thus, in Perek 7 the Rambam is simply reflecting the Torah’s attitude towards Teshuvah specifically, while in Chapt. 10 the Rambam is referring to the attitude one should have for the general observance of the 613 Mitzvot!