What is the way back to true worship after a period of religious languor, during which prayers accumulated and transgressions occurred, with repeated repentance and relapse into sin, and a feeling of the burden of worship?

Sincere repentance to Allah is obligatory, by regretting sins and abandoning them, for the door of repentance is open. For sincere repentance, one should supplicate and seek refuge in Allah, associate with righteous people, listen to beneficial lessons, contemplate death and the Day of Reckoning, and continuously strive against the self, in accordance with His, the Almighty's, saying: "And those who strive for Us - We will surely guide them to Our ways. And indeed, Allah is with the doers of good." (Al-Ankabut: 69).