I've been writing every day for more than two months. I started my 200wordsaday journey not sure if I could keep it going. I thought I would run out of topics, I would forget one day, I would have the will to only do it for a while and stop. I thought I could not reach 200 words consistently. I made it.
In the beginning, when you're excited about a new idea it's easy to find the commitment to be consistent and show up every day. As time goes on it becomes hard. It is not true that once you formed a habit it's natural, once you form a habit you need to be careful to keep it up and don't slip. It is surely easier to do once the habit is formed, but it still requires work on your part.
The hardest days are when you're really busy doing something else. With freelance work I can have days when I work for a few hours and day when I work for 15, they don't happen often, but when they do it is really hard to be able to do anything else. That's why you should always have an article ready for the worst case scenario of it being almost midnight and having written exactly zero words.
If you can write in the morning as soon as you wake up instead of in the evening you have more of a safe cushion and you're surely more rested, but it is not always possible.