By nature, we go to what feels good and try to avoid pain. We got that from cows. Animals don't understand that a painful experience can be beneficial. Try to explain surgery to a cow. Pleasure and suffering are both part of life. But we get to choose which pleasures we want and which suffering we want. And the choice is either the false pleasure that the addiction offers us, or the pleasures that Hashem wants us to have – which are infinitely greater. Do we choose the pain of the spiritual “work-out” or the pain of the disease getting worse?
The Steipler points out in the first volume of Krayna D'igrisah that anyone who keeps away from these forbidden pleasures is promised to receive the pleasures of life from other areas instead. And, conversely, it follows that those who accept upon themselves the suffering that breaking free entails, will save themselves much suffering in other areas of life.
If we decide that no matter how painful it is we won’t give in - even if we feel like we are dying, Hashem takes away the pain from us and it becomes much easier. See this amazing revelation in Chizuk Email #420 on this page.

do you like pain? no? neither do i, and neither does any other human being. the difference between a human vs. an animal is that a human understand what pain is and where it can lead him whereas an animal doesnt, for ex. the pain after working out, a cow would never undertand that it is actually good for it. so we have 2 pains, the pain that eventually gets better in this world and next meaning the pain of self control in this area that after a while gets easier (so i hear) and is worth it for spiritual reasons, or the pain of gettting worse and worse and worse where it even messes up ones life.
the choice is yours.

if we accept pain on ourselves for the sake of spirituality, then in other aspects of life where pain should be found, hashem takes away,
now after this, who would be foolish enough to not accept upon himself this pain for the sake of gaining self control?