Changing it up

I can't believe I did it, but I truly did.  During my 30 minutes on the treadmill yesterday, I ran for 11 of those minutes.  I have never liked to run or jog, just for the sake of doing so.  I never found any thrill in it.  But yesterday I did it for 1/3 of my time and didn't mind it.  Why did I do it?  Just thought I'd change it up a bit.  Could this be a sign of the changing times in my life?