In act 3, scene 1, Hamlet elaborates on whether it is better to live and suffer the "slings and arrows of outrageous fortune" or to die and relieve oneself of constant pain, strife, and heartache. In Hamlet's famous soliloquy, he contemplates suicide and weighs the positives and negatives of dying. Hamlet believes that life is full of pain, agony, and disappointment, which are valid arguments in favor of death. Hamlet is currently experiencing the painful elements of life after losing his father and watching his mother marry his unscrupulous uncle. Despite the numerous positives attached to committing suicide and avoiding life's troubles, Hamlet believes that the fear of what lies beyond existence prevents men from committing suicide. According to Hamlet, the afterlife "puzzles the will" and influences people to bear the "ills we have Than fly to others that we know not of." Essentially, fear of the unknown influences people to suffer the pains of life and endure the constant struggles of human existence. Overall, Hamlet concludes that death makes cowards of us all, which prevents us from committing suicide.
Who would fardels bear,/To grunt and sweat under a wary life,/But the the dread of something after death,/The undiscovered country, from whose bourn/No traveller returns, puzzlles the will,/And makes us rather bear those ills we have/Than fly to other that we know not of?/Thus conscience does make cowards of us all.
Because man does not know what lies beyond the grave, his will is "puzzled," and he bears the vicissitudes of life that he knows as opposed to sufferings which may be beyond the grave--"the dread of something after death"--which he does not know. This fear of the unknown is what "does make cowards of us all," so man does not kill himself.