I went to the gym today for the second consecutive day in this week and although I went to bed last night around 02:00 AM and woke up at about 09:00 AM and felt tired all day long, I did a 1:41 on my Cooper Test practice.
I was not as tired as I was the day before. I think that's because I used a different treadmill. There might be a difference between machines. I started with 7.0 mile per hour and then increased it to 7.1 after 6 min. and 7.2 and up. The same kind of exercise made me tired the night before that.
Anyways I'm goin' again tomorrow and I'll be trying a newer, bigger machine and we'll see the difference.