Inertia

It's very easy to get stuck in a rut, and very hard to get out of it. After all, we are creatures of habit, no?

When you eat a certain way for a period of time, don't exercise, or do anything else over and over again, you end up sort of programmed into that behaviour and, when you start making the change, it can be a bit of a jolt. That's why its important to step back and assess where you are and where you want to be from time to time.

  I often find myself in the middle of a bunch of press ups or half way through a run, thinking of reasons why I should stop. I'm cold, my feet keep slipping, my hands aren't in quite the right place, it looks like rain. The list goes on, and I'm sure we all hear those little voices. The important thing is that we don't engage with this negativity. Even arguing against it is a form of engagement. So how do we deal with it?
By focusing exclusively on the effects of our exercises.
Take press ups. They can be pretty tough, especially when you are reaching your upper limits, you start noticing that maybe its hard to keep your feet from slipping or you really want to change your hand position, but instead, concentrate on the tightening of your abs as you hold your feet in place or the tightness in your arms as the unfamiliar position of your hands work your muscles a little differently.

Running's the same. Bad traction, bumpy trails, soggy shoes, rain, cold, snow...they are all incidentals that don't matter. If its raining, so what? You'll be in the shower soon, anyway.
The trail is slippery, bumpy and uncomfortable? Great, go a little more carefully and enjoy the burn in those muscles as you run,  as long as its safe and you aren't injured, why stop?

When it comes to diet, the same rules apply. We get conditioned to have a huge pile of carbs with each meal, curry and RICE, meat and POTATOES, PASTA and sauce. It sure can feel odd when you start to unburden yourself of these conventions and there are a few "cheats" that can help you adjust, like cauliflower rice, noodled vegetables and other (less harmful) starchy root veg.
Just like with exercise, you need to "be in the moment" and enjoy what you are doing. Adding a ridiculous amount of spinach, kale and whatever other veg you like to a curry is a great way to not miss rice. It adds loads of extra flavour and textures too.
Experiment and don't let the old fashioned rules about how to eat restrict your choices. After all, those rules are largely responsible for the epidemics of obesity, diabetes and other metabolic syndrome diseases that abound.

For a quick lunch, try grilling a cheap fish and making a quick salsa of tomato, cucumber, onion and pepper. Tastes great, is dirt cheap and ready in 10 minutes.
Paleo does not have to be expensive.