Intervals

I did intervals on the treadmill tonight at the gym for an hour.  I've been jogging at 4.7 mph for quite a while, and now that I've hit the 4 mile mark, I want to start improving my speed.  So, I did intervals.  For 20 minutes, I jogged at 4.7 mph for 4 minutes, then at 6.0 mph for 1 minute and kept doing that for the 20 minutes.  Then I changed it up for the next 30 minutes to walking hill intervals at 3.5 mph, going from 6 degree incline, up to 10 degrees and everywhere in between.  I finished with 10 minutes of walking and jogging intervals at 6.0 mph. It really got my heart working, and I sweat a ton. I burned 889 calories in that hour.
It's funny how to this point, jogging at 4.7 was a pretty decent speed for me.  After this one set of 6.0 mph intervals, it seemed 4.7 was a walking pace right when I got done with that minute set.  Nice.  Progress is good.
My 3 month weigh-in is just 12 days away.  What will that bring?  We shall see in a few days!