What happens when one loses the desire to do anything and feels that life requires too much effort?

According to Osho, if nothing seems worth doing, even suicide is still a desire - an escape born of boredom, not fulfillment. Such a negative exit is futile; you will be thrown back into life, because life is a discipline to learn from. Only when life has been lived totally and you are fulfilled can moving into death be a joyous dissolution: samadhi, not suicide.

Feeling like nothing matters is just boredom; don’t escape—live fully until you feel complete, and then endings are peaceful, not desperate.