I am not sure if it is out of laziness, or fear.
I suppose it is also a lethargy of some type. Like you have too many things in the mind and the actions have made you lose up a lot on focus or what you want from life. So this kicks in after some time. Only way to combat this is stacked thinking. You stack good habits so lethargy stays away.
What is interesting in this regard is it is like going to the gym. More energy comes from it, than is taken away. But, have to get off the couch first :)