The yogic sutra duhkha daurmanasya ahgamejayatva svasaprasvasah viksepa sahabhuvah further goes into detailed description of the obstacles that hinders often to attain yogic self-realisation. Several elements can give rise to these, like angst, dejection, instability of the body, and foremost the environmental distractions. These can be conquered by strict yogic disciplines.
duhkha sorrow, pain, grief, distress, unhappiness
daurmanasya mental pain, affliction, dejection, despair
ahgamejayatva unsteadiness of the body
svasaprasvasah inspiration and expiration
viksepa scattered, causing distraction
sahabhuvah existing at the same time, side-by-side, accompanying, concurrent
Sorrow, despair, unsteadiness of the body and irregular breathing further distracts the citta.
Leaving the obstacles mentioned in 1.30, there are four more causes of distraction - sorrow, despair or evil disposition, tremble of the body and irregular or laboured breathing. (Perhaps, laboured breathing shakes the body, creating imbalance, which in turn brings mental distress.) These cause further distractions which excites the mind and consciousness.
These hindrances are of three kinds - self-inflicted (adhyatmika), imbalances of elements in the body (adhibhautika) and problems arising from fate, e.g. genetic defects (adhidaivika). They need to be fought and curbed through yogic disciplines.