Tired after urination indicates a weak kidney and perhaps a weak liver. The weakness of the kidney and perhaps the weakness of the liver may be temporary.
The reason that weakness of the kidney may only be temporary is because the weakness can be induced and it can also be alleviated.
A straight diet of only meat, especially ground pork for three weeks will weaken the kidney so much that the kidney will hurt during urination and one will feel tired after urination. Acidic urine will also make one feel tired after urination.
Vegetables and a vegetarian diet seem to alleviate this tiredness after urination. The reason is that vegetables and a vegetarian diet enhance alkalinity in the urine and greatly reduce urine acidity.
Other remedies to reduce urine acidity include eating 6 to 8 cloves of raw garlic per meal or half an onion raw per meal, and eating ginger or drinking unsweetened ginger tea everyday. Consuming at least a shot of vinegar a day can reduce urine acidity. Red wine and hard liquor also reduce urine acidity.