Oh what a tough topic. Because I agree with keylani, that some of the most challenging aspects are also the most rewarding!
So... no snacks was a huge challenge at first because snacking is such an ingrained habit. For the first probably at least two months I constantly found myself wandering back to the fridge or the pantry and then having to go away empty handed because I knew I wanted to stay on plan. That made me feel deprived, though with careful consideration I knew I wasn't actually hungry and therefore I wasn't actually deprived. I had to do, and still have to do, a lot of thinking about why
I want to eat, and do the hard work of dealing with emotions and/or habits instead of just indulging in food.
Not indulging the food addict in me is slowly enabling me to be a better person - I'm not obsessing over excuses to get out of the house and run errands for the real purpose of hitting a drive-thru or two, and/or to re-stock my favorite goodies for in the pantry.
Another huge challenge is that I'm a stay-at-home mom and therefore do all the meals for my husband (and his brother, who lives with us) and my three young children. So I have a kitchen packed with food, much of it very easy to grab for little hands and quick metabolisms that need snacks every two to three hours. Preparing snacks and meals for my family can be challenging from the very minor aspect of not being able to lick my fingers during prep or clean-up (I'm forever having to wash my hands now), to the major problem of having to prepare separate meals for myself. I rarely manage to get my meal made at the same time as theirs so that I can at least sit with them and we can all eat together, and that's frustrating. I will still sit with them but then have to do clean up and still make my meal and so then meeting the time schedule can be a real challenge (the part about not letting more than five hours pass between meals).
However, what I liked about MRC was the whole foods aspect -everything fresh or frozen and home made, no pre-packaged meals. That's what makes this a lifestyle change for me. If I were buying shakes or frozen meals, eventually I would want to stop because those would be things I was buying in order to "diet". Cooking my own meals is something I will always have to do, even if sometimes I will want to choose something more convenient. And when people ask what I've been doing to get so healthy, I like being able to say I prepare all my meals myself, eat lots of lean protein and fresh vegetables, etc. It's a rewarding feeling to know that I've accomplished this myself, by putting in the time to shop for and prepare healthy things.
No added salt and/or condiments was a challenge at first. Give yourself time to de-tox from the high fat/salt/sugar that is in our diets before MRC. You will learn to appreciate the taste of real food without all the additives. The first time I grilled chicken with Mrs. Dash seasonings I had to laugh. I thought it was amazing that I could rub in that thick of a coating of so many different spices and end up with no flavor! But now I can taste them and enjoy them and it has been rewarding indeed to sit down to each meal and truly be thankful for the good, healthy food that I can eat.
I love my big half-pound salads that I eat daily, but keeping the fresh veggies in stock is a real challenge. Chicken I can throw a big batch in the oven and re-heat four ounce portions all week long (I've found that tilapia doesn't last as long though, and do smaller batches twice a week instead). Vegetables I am forever having to buy more of and peel and chop. I usually have spinach and kale and it spoils quickly. Chopping up cucumbers, celery, tomatoes, etc. has to be done every couple of days, because they spoil quickly too. But the reward is sitting down to a healthy meal that doesn't make me feel bloated or sick afterwards, and doesn't leave me craving more just an hour or so later.
My new body is also challenging and rewarding! Since I carried extra weight from adolescence, I'm discovering a figure that I never knew I had. I think I may be a bit bow-legged! My breasts are a saggy sight indeed, and I still have pretty flabby buns and thighs in spite of getting down to 24% body fat. I wish I'd figured out how to be thin when I was much younger and then I wouldn't have these reminders of how out of shape I was. That's a challenge. However, I feel very confident in my new size 8 skinny jeans (well, my flat booty could use some help!) and everything I try on fits and looks great. I feel confident that with hard work at the gym I'll be able to work on my buns and thighs and regardless, I'd rather look all saggy when I'm naked but great fully dressed, than fat naked and fat fully dressed.
Well I've written a small book here, so best get on with my day! Hope all that helped you some.