For those who've done major sins, how did you find your way back to Allah?

Assalamu alaikum everyone. Sometimes when the sin is really heavy, the feeling of guilt just sticks around, and it feels like saying sorry once might not be enough to truly be forgiven by Allah SWT. I'm trying to do more to make it right. Do I need to keep asking for forgiveness every day? Are there other good deeds I should focus on to help make sure Allah SWT forgives me? And for those who've gone through this, after doing all you can, do you finally feel peace inside? Or does that guilt and shame never really leave you? Jazakum Allahu khayran for sharing your thoughts.