Fatigue....Its again just a perception

Mind is the key to everything....A clichéd statement,but obstentiously true..
I was feeling a bit low on energy today morning after some extra energy was drained out of me.....I, consciously was trying to see if that fatigue was a mental illusion, as my mind knew that i had been working extra or if it was real physical exhaustion(if something like that is true..)...
It was startling to see myself again getting back to normalcy with the same energy as usual after running these thoughts in my head.....
And it was a nice feeling of win,when my mind had to succumb to a self revelation of the trick played on me....