Tired

How come I am always tired?
I thought it was just work, it's too physical, and being on my feet or using a bike all day is wearing me out. But add to that the virus (or is it 'virii?) that seem never ending and I think I have the reason!
I hoped this week off would help but so far no good. The thing is the brain is more tired than the body. This makes me more irritable than normal, and that is normal, and I just have not got the energy to bother or care any more.
What is the answer? Change jobs, well, with the condition of my knee that may happen anyway, but to what? I am getting old, I know nothing, and am discovering just how dumb I have always been! This has not been good for me I can tell you!
Still, I had better go and eat some foul concoction and see if it gives any sign of revival, fish maybe, but I doubt it.
Gloomy? Me? No, this is me positive mate!