It'd be helpful if you posted your budget. I regularly try to challenge everything in my budget (not according to cost, but the way I think about the particular line item). The cool thing about case studies on this forum is that you get tons of extremely objective (and often ruthless) feedback, challenging your previous notions. I find the more I challenge things, the easier it is to shed another layer of attachment to doing things a specific way.
A few thoughts:
-I don't approach it from the standpoint of cutting costs. I start with nothing and add things back in, according to the total dollar amount I have to work with.
-I start with bare bones (as in lose everything and survive on disability benefits or minimum wage) and then work up to middle of the road, and high end. I use the bare bones as the skeleton to which I add a varying amount of fat. Bare bones is not simply the categories: "housing", "food", etc, but varying levels within those categories according to the limits within which I am constrained.
-I always distinguish between needs and wants. In fact, I highlight the wants in my budget so I'm aware of how they affect my decision-making (because of the adaptation tendency you described). I try to see them as the extras they are.
-Within my needs, I also try to regularly think about how good I have it. To be healthy and productive, everyone needs fresh air, clean water, sufficient quantity of whole food (not like Whole Foods whole food though), roof over their head, clothes on their back, way to get from point A to B, a method of communication with others, health care and education. My shelter, air, health care, etc is of particularly good quality. It really puts things into perspective when I'm aware that drinking uncontaminated water is a big deal. Not only are my wants a luxury, but the level of many of my needs are as well.
-Sometimes certain reductions in spending from a previous level also happen without any sacrifice. For example, finding a better deal on your insurance, internet, adjusting your taxes, etc. I wonder what lateral moves you could make?
-Laying it out in ridiculous detail is always helpful. I find most people over-generalize and lump together certain categories. I do it by the penny and flesh out each category. I think that gives me a much more accurate picture of where I'm at and the changes I want to make. When I run the numbers for a cost analysis or whatever, I'm always surprised at how far off my guesstimate was. And it's easier to be aware of opportunity costs when you truly run the numbers for different scenarios. Let's say the eating out supports great friendships, but in doing so you're giving up something else that is important, like reducing your work hours or taking trips you've always dreamed of.
-I'm a huge fan of that adage that it's easier to say no to things when you know your yes. Why do you want to reduce your spending? What are your values and how does your spending line up with those? After I've established my bare bones budget and as I'm adding things back in, I keep my values and priorities front and center. The point for me is that I'm intentional with money and I'm making a conscious decision about how I'm spending it.