"Hashem will disperse you among the nations...and from there you will seek Hashem and you will find Him if you search for Him with your entire heart and soul. When you are afflicted and all these [terrible circumstances] befall you in the end of days, you will return to Hashem and adhere to His word" (Devarim 4, 27-30). The Ohr HaChaim comments that there are two modes of teshuva mentioned in these pesukim. The first possibility for teshuva is one that comes from inside a person without any external impetus. The second is borne out of suffering that besets a person and prods him to repent; and even such a teshuva is welcomed and accepted by Hashem.
Rav Wolbe writes (Ma'amarei Yemei Ratzon pgs. 99-102) that if one can come to repent without any outside cause, it must be that teshuva is a force within a person that drives him to penitence. Thus, we find people that return to Torah true Judaism without anyone arousing them to return; rather, it is an internal yearning of their soul that compels them to revisit their Jewish roots.
According to the Ramban, the Torah is referring to this when it states: "This mitzva is not distanced from you - it is not in the heavens ...nor across the ocean...it is close to you - it is in your mouth and heart to be accomplished (Devarim 30, 11-14). The Ramban explains that no matter where one has strayed, literally or figuratively, teshuva is at his fingertips - to be performed in any place and at any time. He must merely confess his sins ("in your mouth") and repent ("and heart"). The 'closeness' of teshuva is this inner force that pushes us to repent.
The Mashgiach notes, that it is not only Jews who contain such a force; we find such a phenomenon by gentiles too. When the prophet Yonah was commanded to travel to the non-Jewish city of Ninvei and exhort them to repent, he not only refused but also tried to 'run away' from his prophecy. What possessed him to take such drastic measures? He was afraid that the people of Ninvei would accede to his demand to repent. This would be an indictment against the Jewish People who had not taken the prophet's exhortations to heart. Why was Yonah so absolutely sure that these gentiles would repent? It must be that this force which encourages repentance lodges even in the hearts of non-Jews.
Since teshuva is so near to us, and that is why some have made a one hundred eighty degree turnaround in their level of Torah observance, we must wonder why it is that we find many times that as Torah observant Jews we have not repented for the sins that we transgress? Moreover, doing teshuva for these sins seems to pale in comparison to what it must take for someone to muster the courage and willpower to repent and make extreme changes in their life and religious observance. The answer is, that for aveiros that we perceive to be 'insignificant' such as lashon hara, bitul Torah and negative character traits, it is much more difficult to repent. The Gemara tells us that he who commits an aveirah twice has in affect permitted this transgression for himself; he no longer looks at such an action as a sin. This is where the difficulty lies. When one perceives that his entire lifestyle is wrong, such a realization hits him hard and drives him to repent. However, if one has dulled his sensitivity due to repetition of certain sins, he has immobilized the force inside that precipitates teshuva.
What can we do to contend with our lack of remorse? The only answer is to learn mussar on a daily basis. Mussar enlightens us to appreciate the depredation wrought by an aveirah and arouses us to the very teshuva, which in essence is close to our hearts.