Allah Ta’ala says:
“Follow not desire, for it will lead you astray, away from the Path of Allah.”
Rasulullah (saws) said: “A weakling is one who follows his desire and then has hopes on Allah (for reward).”
Desire means preference for things which conflict with the Shariah. The highest degree of such desire is kufr and shirk. The lowest degree is diversion from perfect obedience. Straying from Siratul Mustaqeem (the Straight Path) is common to all forms of tama’.
The remedy for tama’ is mujaahadah– to accustom oneself to oppose the desires of the lowly nafs so that the carnal and material desires of the lowly nafs are subordinated to the Pleasure of Allah Ta’ala. Mujaahadah is to exercise restraint on the demands of the nafs irrespective if such restraint is simple or difficult.