I would like to read through the thread properly soon, but I want to start with saying, that if you have persistence and determination, those attitudes and motivations will already organise discipline naturally.

So if something still gets in the way of your discipline, it's important to examine to what exactly is getting in the way.

And yes, denial of pleasure may be necessary to complete some tasks or achieve certain goals. But I suggest you broaden your repertoire and use other strategies too to be able to do tasks and goals, because not all of them will require so much denial of pleasure. And since the more denial of pleasure you would use where it's not even needed (if that's what the issue is?), the more the motivation for doing the thing will decrease.

It does also matter how much you really align with your motivation for the task or goal, so, I could go deeper into the topic but that's enough for now, I don't want to repeat stuff before reading the rest of the topic. In case it's all been posted already.

PS: I realise this OP isn't fresh but I hope it's OK to post anyway, in case someone finds it helpful? I didn't see a rule against posting in old threads (?)