I agree. Nothing will happen if you stay in a corner and cry. You'll be wasting so much time, because instead of going to the mall out with your friends or watching that new movie, or going swimming at the beach, you choose to cage yourself, wear a frown, and be sad.
Yes, you will be wasting time, and yes, this is very true, but despite that, I have to say that I do this, and it is very effective. Every time.
I know that it doesn't seem very helpful, but whenever I sob in a corner for one whole hour, it kind of makes me feel better. I think of it as flushing all my sadness out into the drain, while thinking of the situation that happened. If I fought with a friend of mine, I try to put myself in another person's shoes and think of the advice that I'd get. Then I think of the situation thoroughly, and finally, with a new found solution, I apply it to my life and not regret a single moment of the art of time wasting.
Life will be short if you waste it, but if you keep going on and pretend to be strong, it won't be very worth it. It's okay to be sad, but also remember that no one should punish theirselves to be sad forever.