How can one regain zeal and determination in acts of worship, in honoring one's parents, and in academic excellence after a decline in all these aspects?

Lethargy is a natural phenomenon, and faith increases and decreases.

Lethargy is treated by being certain that there is no power or strength except with Allah, by supplicating to Him, by striving for good companionship and avoiding bad company, by frequently remembering death and contemplating Allah's signs, and by diversifying acts of worship and recreation within permissible limits.

Honoring one's mother is among the greatest causes for Allah's pleasure and success. Therefore, you must address her with respect, gentleness, humility, and reverence, for Allah the Almighty says: "So do not say to them [anything that indicates] displeasure and do not reprimand them but speak to them a noble word. And lower to them the wing of humility out of mercy and say, 'My Lord, have mercy upon them as they brought me up [when I was] small.'" The mother's ill-treatment does not justify disobedience; rather, she must be honored and treated with good companionship.