How long do you need to force yourself before it starts to come naturally?

I have never been considered a lazy person by those around me, that is a label I put on myself, I have asked my support network over and over if I am just lazy and it is a resounding no. But I still feel lazy. The last few months (besides a few days here and there) it has been a constant inner battle to do more, be more. When I do more the only thing I get out of it is tiredness. No enjoyment or happiness, sometimes I am just content. How long do I have to keep forcing myself? Will it ever be easier? I remember a time when it was.