Whenever we think about all the sins that we've done, do our hearts ache? Do we feel a totally remorseful feeling when we recall our mistakes we've committed one time ago?
Hopefully we do. And it will be better if the pain we got leads us to crying and wailing to Allah, pleading Him to forgive each and every sin that has been written in our books. We might forget certain sins that we've done, due to the countless amount of them, but truthfully, Allah never forgets. He remembers every wrong deed of us, no matter how long we've been drifted away from all black days of us.
Among the conditions of the tawbah to be accepted is; for us to feel regret. And one way to prove that we really do feel regret about our sins is by having the pain residing in heart. Wallahi it's not easy to have such feeling. It's hard for us to honestly feel contrite about our past sins. It's hard, but not impossible. The fact that you feel like repenting is already a sign that Allah wants to forgive you.
We really need to remind ourselves to have a correct understanding on how to repent. Don't ask whether Allah will accept our repentance, rather, ask ourselves whether we've repented correctly.
He is waiting for us to return to Him. He is very happy when we want to return to the right path. May we all will gather under His mercy one day. InshaAllah.