What is penance for sexual sin in the Orthodox Church?

We need penance. Everyone works like this, but especially us men: we need to know there is a discipline involved when we commit a sin we shouldn't be doing. The church fathers have routinely said that especially when someone defiles the temple of the Holy Spirit, they need to be kept from Holy Communion for a period of time. Sometimes that's two weeks, sometimes it's forty days, which is the norm.

Sometimes it's extra prostrations, sometimes extra fasting. As St Joseph the Hesychast said, you drive a nail out with a nail. When a nail gets sunk too far into a board, you can't hook it and bring it out. You put another nail on it, hit that nail, and drive the first one out through the board. The penance is the discipline that we know is waiting for us when we give over to these base desires.