Young-, Middle-, and Old-age Man

Sometimes I live in the past, roaming around old memories in my head. This is becoming more and more prevalent in my life. I don't like it. It's a sure sign of the onset of middle age. Some observations:

• Young-age man obsesses about the future.
  
• Middle-age man (involuntarily) contemplates why the present is as is, given the past which led to it.
  
• Old-age man, I take it as a guess, (involuntarily) continually reviews his past.