So the zen master took a deep breath and said there are physical prisons.... and prisons by choice -- very few are locked in physical prisons, but almost everyone is locked in prisons they choose:
1) prison to the past - holding on so hard to the past you lock yourself away from the present
2) prison of wanting to impress - doing everything in power to impress others, without taking care of yourself
3) prison of false belief - clinging to things you were always told were true, even though your heart knows they are false.
4) prison of selfishness - thinking you are better than anyone else even though in truth we are all the same.
In the words of Bob Marley: "Emancipate yourself from mental slavery, only by ourselves can we free our minds."