not able to go on
Having no hope of or ability to continue (doing something). After walking through the desert for nearly two hours, I wasn't able to go on any further. I'm sorry, but I'm not able to go on working for you.
not able to go on
unable to continue (doing something—even living). (Not able to is often expressed as can't.) I just can't go on this way. Before her death, she left a note saying she was not able to go on.