For years, I loved getting up around 5 or 6am to get my workout in. It energized me for the day not to mention it was nice not having to worry about fitting it in later in the day. But as the years have gone on I have noticed that my body doesn't like it as much. I'm finding that I feel better doing it later in the day and I get a better workout in. So I was wondering if our bodies rhythms change with time? Have any of you experienced this?