It is hard, you either need to carefully plan your diet or you're risking ruining your health far more than usual. However, it's very easy to greatly reduce your meat intake - just looking around for vegan options lets you put a lot of variety into your daily diet and it turns out that it can be tasty even if you generally hate vegetables, like I do. Even though I sometimes still choose meat out of preference when eating out, I would never expect that I would be able to actively prefer vege and vegan options in so many cases until I tried :) Ended up in me always checking (and contributing to) OpenVegeMap when looking for someplace to eat in a new area.

Choosing one day a week to be completely miserable sounds like a much worse path to veganism than cutting back one thing at a time.

You could start by going vegetarian instead by choosing to eat a cheese pizza instead of a hamburger. There's a wide world between carnivore and Jainist vegan. There's also a ton of much better vegan/vegetarian meat replacements available than just a few years ago.

As a vegetable hater that was a misconception that I used to have. Turned out that in most cases I even prefer vegan meat substitutes to real meat now for their taste and texture (they can be pretty similar, but the slight differences IMO work against meat).

Also, you don't have to be miserable. There are tons of foods that a lot of people find delicious that aren't meat. You can use substitutes (tvp or lentil/walnuts for tacos, tofu in a stir fry, etc).

Different approaches work for different people. Personally I just went cold turkey but for a lot of people it's easier to set aside a day to try it. Whatever works for you is fine, of course. A lot of people find that, far from being miserable, they feel better and enjoy the food they're eating.