For my first round of 30-day challenges, I don't think I did that bad. I used the Pimsleur language Spanish I program and only missed about 5 days out of the month. The days that I missed were mostly early in the month, as I was adjusting this new idea of these challenges. Not only was it difficult to remember this specific challenge, but I forgot that I was even doing these challenges a couple of times. Hopefully, it will get easier as time goes on.
While I'm not a big believer in New Year's Resolutions, I have experimented in the past with attempting to do something for a month to see if I want it as a new habit. Apparently research suggests that you should attempt something for three weeks to develop a new habit, though I have never bothered to look up the original articles. One month I tried to eat only homemade bread, cooked either in the oven or bread machine.