Comment by supertofu

In theravada buddhism, this is called applying the faculty of wise attention. We have zero control over our thoughts, but we have control over the object of our attention (and it improves with practice).

When unpleasant thoughts arise, the (canonical Buddhist) strategy is to move your attention to something (anything!) else.

Using mantra (prayer) or force of will ("I close my attention to this thought") are both applications of the technique.