How can one more effectively get rid of excessive thoughts about sex, especially with repentance from masturbation and watching sexual videos, persistence in seeking forgiveness, and changing one's thinking?

The best remedy for someone facing this problem is marriage, because it protects one from the forbidden and directs sexual energy into what is permissible. If marriage is not possible, then one should increase voluntary fasting and the remembrance of Allah. One should also distance oneself from everything that incites desire. The greatest aid in controlling oneself is to remember death, the grave, and the horrors of the Day of Resurrection.