I know what I need to do.
I know how to do it.
I know why I'm doing it.
So why can't I just do it!
Let me put it another way:
I know that I need to lose weight by following a sensible diet and exercising and that by doing it I'll be helping my PCOS symptoms and improving our chances of having a baby. So, why can't I just do it!!
I gave up smoking relatively easily. I consider myself an ex smoker - I haven't craved a cigarette in such a long time that I don't even remember what it was like to be one of those people that had to nip out for a smoke on a night out - I really don't.
So why can't I apply that same will power to losing weight. The end goal of losing weight is a much bigger (and better) one than the end goal of stopping smoking (which, at the time was to save money).
Maybe that's what the problem is.