Just ramble about this and that.

Haven't you had any interesting experience recently
or haven't you read anything impressive article in a
newspaper or a book?
Anyhow what's on your mind now?
Talking to yourself is also OK. 
 

Life's purpose and goal is to be happy.

Sex makes us happy.

=>　Part of life's purpose and goal is to have sex.

In fact, it is, by the definition of life. If it weren't for sex, we wouldn't exist. We are meant to experience pleasure - natural selection provided us with a pleasure system specially for this.