what kind of imprisonment? that of desires, heaviness, laziness etc. the question of course is how does one get out of it? "a person must know that he didn't come to this world in order to rest but rather work and toil" the starting point of getting out of the habit of heaviness of the world- we need to know that we are in this world - not to rest, but rather for work and toil. so when you know that now is not the time to rest- after 120 years, the gemara says that the daughters of rav hisda saw him getting older- and he would sit for hours upon hours and learn torah so they had mercy on him- he's an old man, he needs to sleep- they told him, father- go to sleep you're already learning for so many hours...so he replied, soon i will be sleeping for a very long time