And the recipe is one only:

Make peace with yourself, lessen the expectation and understand that happiness is not having, is being.

Here are some things to seriously think about... Fist of all we have to be in peace with ourselves, calm, serene, on the inside. It is the only way to be good in the outside and, above all, to the others. I've already figured it all out...the only thing I can't understand is how to change it... This is really frustrating! Enough with the expectations! It never lead me anywhere and serve only to make me a much more insecure and fragile person. It makes me create illusions and dreams that, in the most of the times, aren't real and then I fall, again and again... So, stop with all the expectations!

Do not regret! Other huge advice. As a famous quote from Victoria Holt use to tell "Never regret. If it's good, it's wonderful. If it's bad, it's experience." So try, try it all! Remember you have both 50% chances to like it or not, of being a good or a bad thing, to change things for the best or worse... You never know, but try! Stand still seeing life goes by will not bring you anything new... So try, make mistakes and learn.
Worry about those who are good for you and forget the rest. If people are not good for you they sure don't deserve you to be good for them so just forget about those and start caring about those who matter.

I'm still not sure that everything happens for a reason but I hope I can figure it out real soon. I want to believe in it and I'm sure that, sooner or latter I'll have my answer :)