T50 (Tinyana) PNC - Machshavah Like Reins of a Horse; Yetzer Knocks Repeatedly

Thought is in the hand of a person to direct it as he wills, to whatever place he wants. As explained elsewhere, two thoughts cannot be present together at all. Even when sometimes his machshavah goes flying and wandering to other and foreign matters, it is in his hand to bring it back and force it back, against its will, onto the straight path — to think what is fitting. It is exactly like a horse that veers off the road to another path: one grabs it by the reins and pulls it back, against its will, onto the straight road. So too with thought: one can grab it forcibly and return it to the proper way.

The yetzer ha-ra knocks at a person each time and pushes him to whatever it pushes him to. Even if a person doesn't listen and turns his back, the yetzer keeps knocking — a second time, third, fourth, and more. But if a person stays firm in his daas, stubborn against the yetzer, paying him no attention at all, then the yetzer departs and goes off. So too with tefillah: foreign thoughts come to confuse him over and over, time after time. He must stay strong, not look at the thought at all, in any way — and then it departs. (See more on this elsewhere.)