I didn't run yesterday, because we had two grandchildren with us all day. Normally, I would run on Monday, Wednesday, and Saturday. This week I'm running on Tuesday, Thursday, and Saturday.
After my first minute of running, my left leg was really tired (no pain, just tired), and I thought to myself, "Oh Oh, I'm in trouble". However, after one minute of walking, my leg felt fine, so I did a second minute of running and my leg felt tired again. Again, after a minute of walking, my leg felt fine. Fortunately, my leg felt fine after one mile, and I finished my run/walk with no problems. Apparently, my leg needed to get warmed up, and that required a mile of run/walk.
I went south from 100th South to the tunnel under 106th South and back. My wife wasn't with me today.