What keeps you motivated?

Hey this might sound a little off but I just want to know what keeps you guys motivated ...... And what do you do when you feel a little down some day ? Felling a little down today ....reason ? Well I don't know the reason ....it happens with me a lot like Sometime I don't know what happens but I'll just go into deep thinking about anything....and sometimes even when I'm in the middle of something and all of a sudden a realisation hits me that I'm not okay . I might not reply to the comments but I will definitely read them.