Trying to cry is also a distraction
Even though crying before Hashem Yisburach with entreaties and beseeching is extremely good, even still, when a person says Psalms or other entreaties and supplications, or converses personally with his Creator, and he thinks and anticipates, and looks mindfully all the time that he should cry and shed tears, this also is a (distracting) foreign thought, and confuses the kavana (-concentration, intention). Because the main thing is – that he should concentrate his mind to say the words truly with all his heart, that he should incline his ear and his heart to hear what he is expressing with his mouth, and if he is aroused to cry, how wonderful – and if not, he should not confuse his concentrations for this.
Na Nach Nachma Nachman MayUman
(Likutay Moharan II, Torah 95; Outpouring of the Soul 3)