Karlisbad said:
Then, the question is how could you improve your "creativity", of course i believe you must make an effort but..how?

is there a formula for creativity or learning?.
Creativity and learning are two different things, almost opposites in important ways. I'll get back to that.
There isn't a formula for creativity, but there are specific kinds of exercises you can do to cultivate it. The best to start with is the same kind of free association Freud developed for psychoanalysis. You lie down, get as comfortable as possible, and speak your stream of consciousness out loud. You say whatever comes into your head: censor nothing, everything is valid and permitted.
You can do the same in a written version: just sit down and write out your stream of consciousness.
Back when I was studying theater in college we did an excercise called a "body river." This involved both speaking and moving to your stream of consciousness. Not acting it out, but accompanying it with whatever physical gestures your body felt like doing.
The reason excercises like these work is because everyone is already very creative but we all have learned to put a lid on it for, pretty reasonable, social reasons. In one of these exercises it would be perfectly OK to spew a stream of obscenities or digress into repeating the peculiar word "pupae" over and over. You can't do that in most social settings. Even close friends won't tolerate
everything a person feels like doing. But to be creative a person has to feel perfectly at ease exploring any weird notion that pops into their head. So you set aside a "safe" time and place to do this. What comes out is all raw material that has to be picked through later and edited. Most of it,
most of it is junk and you throw it away: to get to the diamonds, you have to dig up a lot of dirt.
Creativity is wedded to the act of self expression. You are letting the stuff inside you out. Learning is the opposite: you put your self to rest and let the outside world in. You allow yourself to listen to and understand information from people and sources outside yourself. I think learning is harder. It requires more sustained attention and discipline.