I'm one of these guys who gives it ALL on retreat -- sit early, sit late, don't move, immediately to walking meditation, keep walking until bell. However, my daily practice was weak. There were always way more enjoyable things I could be doing, so I wouldn't sit or I would stop (did not set a timer of any kind). And there was no temporary, external structure that I would give myself over to.
So why were other things so much more enjoyable? I believe because I had aversion to the practice, aversion to the hindrances, identifying with the hindrances, aversion to me, feeling like a failure -- heck, it is way more pleasant to do things that do not result in continuous failure!
Because, at some point I really committed (a different story), I began to sit regularly enough that I almost had to learn to let go of identification (hindrances are "just hindrances," not "me") and aversion -- just too much suffering. I guess the point I'm trying to make here is that if aversion is what is holding one back, doing it anyway may help reduce the aversion -- and for me, Metta practice has really helped with that. As I alluded to, what gets one to the point of committing certainly varies; perhaps hearing that the aversion can diminish can be an influence.
"Why is it, Master Kaccana, that ascetics fight with ascetics?"
"It is, brahmin, because of attachment to views, adherence to views, fixation on views, addiction to views, obsession with views, holding firmly to views that ascetics fight with ascetics" (AN 2: iv, 6, abridged).
Kindly eyes, not verbal daggers.