I start a contest. My mind feels great, it feels sharp and quick (for my sharpness and quickness standards), after the contest I feel excelent about my performance and feel I did as well as I could.

Next contest, my mind... well... I might be drunk as well, I can't even read the statements, feel like I can't do easy stuff, think too many things that later find out to be obviously wrong...

Can you relate to this?

My point is that some days I just simply can not wake up my mind and it's really frustrating, even for days I just want to study or train.

So I'd like to know, do you have some warm-up exercises for your mind that you would like to share? Exercises or routines you do before training/studying/competing? Saying the alphabet backwards, trying to calculate Fibonacci mentally up to fib(100), I don't know, what do you do? :)