We all contemplate death at some stage in our lives. how far our own mortality will take us.<br />
But if you are thinking about ending your own life, then yes is can be bad for you because it will put you into a state of depression.<br />
We all have low points in life, but there are the better times as well.
Certainly at your age it isn't good if you think dying is something you'd like to do. If you're just pondering eventual inevitability, it's pretty normal and wise to think about sometimes.