No goal in sight

I've been thinking a lot about this and its kinda worrying. I've always had it pretty easy in life (well except for all the normal stuff everyone goes through) but like I've never had to try very hard before and I think thats the reason why I now don't really know how to get myself focused and determined. I managed to more or less slide through school with not super good grades but still decent enough and I managed to get myself to Cambodia without too much trouble and I think no that I'm here I don't really have any other goal like up until now my life have been more or less fixed on before hand and now there isnt a new plan for the rest of it and I feel incapable of making one up myself and I'm just scared that I will wake up one day when I'm forty and realise that I haven't done anything useful with my life or even worse not wake up at all and just go through all of life without having accomplished anything. And I look around and there are so many determined people and people with a goal that they are willing to fight for and I don't feel anything. I'm pretty satisfied sitting down on my butt sipping fruitshakes thinking about clothes, boys and friends (Jup thats how shallow I am, its been concluded) and alternating with this sitting on my butt sipping fruitshakes together with boys or friends wearing pretty clothes. But when I think of the fact that I could be satsified with this I feel a strong sense of panic in my chest and I don't want that to be all I desire but I don't know how to get around this and how to get a goal or cause that I am willing to struggle for and to put some effort in. Its a pretty desperate feeling not knowing what to do with your life. Aweful huh.. some people would do anything in the world to have the choices I have the possibility to make and I'm just too lazy and ungrateful to make the most of it.