5 miles in 51:11...yuck

Not a great run...started out with a nice pace and just ran out of gas. Was aiming for a 47 or so, and was on pace when I got to the halfway point at 23:40 so I thought I was on my way...but ran out of gas...I guess either I am not capable of maintaining that pace due to lack of conditioning, or maybe my head just was not ready.