Our Minds are highly programmable. Like in outer space, without much influence of gravity, whichever direction you "push" an object floating over there, it will continue on that new path, and if you push it towards another direction, it will take the new direction and continue on its way. Likewise, in our usual life, our mind is used to enjoying the objects of senses, we are always in internal dialogue, we interested in new things (latest TV episode of your serial, news, family matters, parties, gossip etc). But if you put effort and train your mind to observe the breath silent, as time passes on, with your perseverance, your mind will "get used to" observing the breath. Now you will actually have to put effort to again partake in mundane social matters and life. For example, that mundane state of mind is the "ground state" which the mind automatically assumes when you are not holding the monkey mind by observation, but if you practice anapana for a prolonged time, the observation of breath, will become the new "ground state" to which the mind will automatically revert if you are not especially making it indulge back in the normal world.
I personally think that Mahayana means not allowing the mind to develop any such "ground state" at all, not even the Jhanas.
That is my personal opinion and I appreciate if I am corrected by more knowledgeable members.