"The moment you know that this is the person with whom you want to spend the rest of your life, you should start the engagement process. Once you know this, the nature of the relationship changes. You view actions differently, the pressure to have sex increases, and your relationship with others is affected. If you're considering getting engaged, write out the sentence Staying married is hard work fifty times. ...Though I say this with some humor, I think these points bear repeating: Don't underestimate the work involved, but don't panic either."