Is what the questioner feels—namely, a lack of success in studies, disturbed sleep, a lack of blessing in time, and harm from colleagues—attributable to Allah's displeasure with him due to his sins, or is it incumbent upon him to strive against his soul to achieve his objective?

A Muslim should not surrender to intrusive thoughts or helplessness. Rather, they should be keen on what benefits them in this world and the hereafter, seeking assistance from Allah Almighty. A strong believer who loves good strives diligently and seeks Allah's help, never giving up. If something undesirable befalls them, they should say: "Qaddara Allahu wa ma shaa'a fa'al" (Allah has decreed, and what He wills, He does), because saying "if only" opens the door to the work of Satan.

Allah's predestination of affairs does not mean abandoning the means. Indeed, humans are commanded to work and strive, for everyone is facilitated for what they were created for. Sins can be a reason for being deprived of good, but not every failure is a punishment. The purpose of self-reckoning is repentance and abandoning disobedience, not justifying helplessness.

A Muslim must be moderate in self-reckoning and avoid despair and despondency. In summary: seek Allah's help, supplicate to Him, exert your effort in seeking good, and strive to overcome obstacles. If you are overcome in a matter after exerting the means, then patience and contentment with Allah's decree are the solution.