Demotivation and Nihilism
This is what happens when you try to lead a monk life without leaving lay life.
Why not ask yourself the question "what am I doing in lay life if I'm not motivated to achieve the goals of lay life?"

This isn't the fault of Theravada Buddhism. It's the fault of the individual who cannot pick one lifestyle. Lethargy or laziness is one of the five hindrances and there's no place for it in Theravada Buddhism, whichever lifestyle you choose. 

If a certain goal does not interest you, stop bothering about it and work towards the goal that appeals to you. If no goal in lay life appeals to you, get ordained and practice diligently towards attaining enlightenment.