Your energy might have been what enabled you to complete the workout routine every day, rather than the workout routine being the cause of your energy. How did things change when you stopped the routine?
Anybody who's done something like the above knows that the early morning workout is the ignitor that gets you on track, syncs your circadian rhythm, etc.
When you sleep in etc, that's when you start to get low energy and lethargic.
"Anybody"? I tried exercising early in the morning for several months and hated it. It turned out that 1) I got very sleepy during the day 2) I can't exercise as hard as usual because I'm just not in the right mood that early.
When you sleep in etc, that's when you start to get low energy and lethargic.