Why i am always get attracted with things which we dont get easily!!!

I was thinking sometime back that in past i had so many chances either personal or professional way that i could have got it very easily but i dont know i always prefer for things which i dont have and i always get attracted which is difficult.. I think its human psychology which i dont understand but i just observed from my past that i always feel happy when things are new or difficult or not got easily although other path is easy..............