People who say that life is not worthwhile are really saying that they themselves have no personal goals which are worthwhile. Get yourself a goal worth working for. Better still, get yourself a project. Always have something ahead of you to look forward to -- to work for and hope for.
Maxwell Maltz (1899-1975) was a cosmetic surgeon who developed Psycho-Cybernetics, a system of ideas that can be employed to improve one's self image and in turn lead a more successful and fulfilling life. He wrote several books, among which Psycho-Cybernetics was a long-time bestseller that undoubtedly influenced many subsequent self-help teachers.