Lack of Grasping of the Object of Meditation
Meditation is non-doing.  However, you must prepare and devote time and space to this "non-doing."  That preparation is infact an act of doing in an effort to partake in an act of non-doing.  What is in the process of being done has a goal.  The goal is to partake in an endeavor of what is not being done.  Meditation by it's very nature creates a paradox for the participant.  The answer is to relinquish the paradox.  How does one do this ?  The act, or non-act if you will, must at first be recognizable.  Then there is a calling to fuse the act and the participant into one state of beingness. How does one transmute?  If you were to focus on the 5 strengths that might be of some use.  Conviction, persistence,mindfulness, concentration and discernment can create a looping effect in the mind whereby the one meditating can constantly reflect on how each strength effects not only the current state of mind but also the relation of the 5 strengths themselves.   The distraction of the mind becomes the essence of the meditation.  In order to break through the thraldom of the senses and the inertia of conceptualized thought patterns the mind needs to be distracted.  To have a goal in meditating is not the answer.  To be able to transmute the energy of who and what is currently proclivitating in and around us into what is our true nature is meditation.  I hope this helps.