I recently completed the book, The Power of Habit, masterfully conceived by Charles Duhigg. It clearly outlines how habits rule our lives, and how to change them. I often consider how the transition to a minimalist lifestyle is simply a transition of habits; replacing one trigger with a new routine to achieve a similar resulting sensation.
For example, I don't purchase plastic sandwich bags. Instead, when I "need" a sandwich bag, I grab a reusable sandwich bag or container. To establish this new habit, I had to procure a few new items, but now that I'm set up, it's easy.
Some habits are harder to undo. I used to like buying magazines. Not often, but typically at airports or grocery stores. Now when I see a magazine to which my brain exclaims "I want to buy you!," I find other ways to give myself a little boost, to replace the satisfaction I used to get from making the purchase. It might be to remind myself that I'm saving $5, or that I've done a great job of not once buying a magazine in the past three years. I always feel better walking past the magazines than I did when I used to purchase them. And by the time I'm on to my next activity, I've already forgotten about it.
Anything you fear will be too hard to change is merely a habit to recreate. It can be a fun challenge and one that I highly recommend starting today. Pick one aspect of your daily or weekly routine that you can change for the more sustainable alternative. Give yourself a couple months to fully integrate it into your life. Perhaps start with something simple and after you've changed your first habit, move onto something a bit more difficult.