What exactly is chilling out??

Few of my well-wishers here in the states suggest me that I should learn not to take life so seriously. How exactly do you define the seriousness??

I see a lot of people here around me who get drunk at every chance they get, roam around, party whenever they want to and most ridiculous of all, relying on others to clear up the mess they leave on projects/studies. I mean I am nobody to judge and I hardly care but it never ceases to amaze me.

I prefer to keep things simple. Work, Study and Enjoy. There has to be a certain theme or flow to life that you have to decide. I have this bad habit of getting over anxious about things and getting tensed about things that are not in my control. But isn't that perfectly okay? Everybody gets frustrated. You put in hard ass work to achieve things and in due time when you fail or rather fall short then it does get to your head. It is paramount that you keep calm and carry on but then in the heat of the moment, it does frustrate you.
Also, I let others' gain affect me which is very wrong. I mean, I am not sulking that others get things. I just feel sorry for myself and get angry for myself at falling short. I don't know why I keep doing it. But then that is how it's been. I am more disappointed on myself than jealous for others.
I am done asking the questions, I don't have the answers. Does anybody?