I've known palliative care doctors who will administer an extra dose of morphine to stop the heart of patients in the final stages of a cancer death, where there is no hope and the family is praying for death to end the loved one's suffering, and the loved one is already comatose. But having nothing left to live for is essentially severe depression. We all have something to live for, if we are capable of caring to look for it. If you have someone with these suicidal tendencies in your life, help them to get medical attention, for their survival, immediately.