Where did that hour go?

I've been really confused as to why I wasn't able to walk from my house to the Second City in an hour.

Like, it made no sense to me how this walk that I've gone on before, suddenly was taking me a lot longer.

Then I started realizing the "hour" that I had.
Class started at 7. I wanted to be there at 6:50 to change my clothes. So there my hour was is now 50 minutes.
Then I kept running back in when I realized I forgot things, like, my water bottle, and stuff. So, I wasn't actually out of my house and walking until 6:10. And I can verify this because I called my sister once I left, and my phone says 6:10. So then the hour I planned shrunk again to 40 minutes.
And for the 10 minutes I was talking to her I was walking at quiet the leisurely pace because I was chatting with my sister and wasn't paying attention. Now I understand why from 6:20 to 6:50 I was briskly walking. And by briskly it, may have been a light jog at some points.