How to strengthen ourselves for the unseen war and against the evilt thoughts?

The best way to gather your thoughts is having a main one that helps you to recognise the others, and to cast the evil and support the good ones. The easiest way is this prayer: ‘Lord Jesus Christ, Son of God, have mercy on me, a sinner!’ We say this in order to be able to be steadfast in good thoughts.

An evil thought is casted only with a good one. Of course we have to keep from the source of multiplication of the evil thoughts, otherwise you become the one that multiplies them, and in this case, there can be no peace of the soul but in time. 

(Translated from Arhimandrit Teofil Părăian, Iubirea de aproapele – ajutor pentru bucuria vieții, Editura Doxologia, Iași, 2014, pp. 73-74)