7km doesn't seem bad to me. But it's a lot warmer here in Phoenix so I can't say. Could it be the cold?

But I'm thinking diet. Do you breakfast properly? I also usually have nuts and/or fruit for a mid morning snack. Disclaimer: Part of my breakfast is coffee.

For me the ride in actually gives me energy. I'm not normally a morning person. But I'm better mornings and afternoons for the riding. My ride is 5mi or 8km each way. But as I said it's an easy 8km, no hills and very little subfreezing weather.