WARNING! THIS IS VERY SERIOUS, YOU CAN SAVE A LIFE WITH IT SO NEVER EVER EVER DO ANYTHING AGAINST THIS RULE!
Be nice and kind to anyone
Even if you feel like shit, even if you feel like dying in every minute, be nice and kind. You don't have to like everybody and love everbody. But did you smiled at a stranger today? What was the nicest thing you've done something today? Did you walk over to the bullied kid in school or did you ever stand up for him/her?
I bet you have't, have you?
I know, you may think "What is she saying here? I want to be happy not making others happy?"
Well, easy story to explain. A smile at a stranger can save a life. Just imagine you're in the bus/train to school and you sit next to a random stranger. Before you sit down, why not smile at him/her? It's easy and can maybe save his/her life.
Just imagine this person is sitting there and is planning to kill him-/herself. And than, you come over and smile at them. Because just a little smile gives hope and makes you feel loved and liked.
You may don't get the same back, but there will be a day on which someone will come over to you and thank you. Or a moment where you get it back. It may takes time, and you may don't get everything back because maybe you see the stranger you smiled at never ever again. But I promise you, you will :)
Just try it, it makes you happy also.