As astudent in chinese medicine, I will answer it through this vision. Lack of motivation, is seen as lack of will, so a weakness of the kidneys. The reason could be a poor life style, diet, or exhaustion. So there is two things you have to do to resolve this problem, first getting rid of what is attacking your kidneys, secondly, strengthening them.
1st what is attacking kidneys: all kind of addictions in its large meaning (substance such as alcohol/tabaco/drugs/ foods, but also behaviors like playing video games/Facebook for hours, too much sport etc.) Not resting fully at night for a long period of time ( like getting use to not getting to bed before midnight) not good diet, like a big amount of processed food, low portion of fresh food, chemicals such as sweeteners/msg/flavors/colorants, low quality oil (fast food fries etc.), big amount of salty food
2nd, to strengthen your kidneys: Beans/lentils, reduce the amount of salt in the food, dark fruits like blueberries, having a minimum amount of nuts and seeds everyday (particularly chestnuts/walnuts) Having a king's breakfast, emperor's lunch and beggar's dinner. A warm breakfast with cinnamon for example is advised.