40 Minute Run

Did a trail run with my brother in Florida. Ran 20 minutes, walked a minute, ran 5, walked one, until we hit 42 minutes, then we walked the last short bit back. My body felt dead today and I didn't have the best wind. I don't know if it was the climate (it wasn't too humid), lifting weights yesterday as well as a 7 minute treadmill, running maybe faster than I thought (there were no mileage markers) or just not being in as good a shape I would like to be.