Exercise and the Endorphin Zone

This weekend I went to the gym and was on the elliptical machine.  I wasn't really all that into it, but was making myself do it anyway.  So I cranked up my iPod and trudged my way through it. 
I set the timer for 30 minutes, but after about 15 minutes I started to really get into a groove with my music and going a little faster, and as I neared the cutoff time that I'd set for myself, I found that I wasn't ready to stop. 
Quite the contrary, I felt great and wanted to keep going! 
So I bumped the timer up 3 more minutes, and started going faster and faster, man I felt great!  When those 3 minutes were about up, I still wasn't ready to stop, so I bumped it up 4 more.  I had an appointment to go to after the gym, so I kept an eye on the clock and kept bumping up the minutes until I had to leave. 
I hit that endorphin zone and felt like I could've gone on for a couple of hours.  It was such a great feeling, and I felt so strong and healthy that I wanted to keep it going.
I did manage to drag myself off the elliptical before I killed myself (LOL) but am really looking forward to going back tonight so I can find that zone again.  Try it sometime, it's AWESOME!!