It's about willpower indeed. You acknowledged your lifestyle had a negative impact and therefor that lifestyle has to change. Acknowledgement can lead to action. Now just do it.

Perhaps you can work with smaller steps. And as you get used to less of this and less of that, adjust the volume until cutting it all. Smaller steps creates room for more milestones to be proud of during your road to getting where you want to get.

I hope you succeed mate.