When I say tiring, I mean exhausted. Some people think that after a hard day of work they are tired. But in reality its comes down to their intake and expenditures. For example, if you intake nothing but coffee, chips, pizza, and microwaved meals and alcohol (the typical workaholic menu), you will probably feel exhausted after a regular day of work. But lets say on the other end of the spectrum, you eat nearly perfectly. For example, all the food you eat comes fresh, and not preserved at all (yes expensive and time consuming, but VERY healthy). You eat just enough to get you by without over-indulging, or under-eating. Just enough carbs to replenish your glycogen levels, some healthy fats that your body needs to function. And just enough protein to repair and rebuild all the tissue in your body. And lets not forget lots of water, and plenty of REM sleep (deep sleep).
Now lets look back...are you exhausted because of the amount of energy you expelled? Or are you tired due to a lack of actual energy being ingested? 99.9% of the population either gets too much energy (and not enough exercise) causing weight gain, or not enough energy (and too much exercise), causing injuries or something of the sort.
Saturday and Sunday, I can tell you I didn't meet my recommended nutritional needs, causing massive amounts of tiredness, and stomach aches. Thus my output level of success in what I was doing dropped dramatically.
So next time you blame your tiredness on the amount of work/energy being expelled (used), just think back....did you get enough sleep in the last couple weeks? Did you get proper nutrition leading up to that point, and during that day? Did you get enough water? Did you have the proper mindset going into the point that begun feeling tired?
Here's a couple vids since I last posted.