After reading Eight Years a Tertiary, a woman I know asked, "of all the requirements of a Third Order Tertiary...which do you find to be the most difficult?"
Unlearning the bad habits I acquired before I joined the 3rd Order.
Much of living a Catholic life is developing the right customs and habits and then being faithful to them. Daily Mass was not possible until a traditional priest was stationed in Atlanta, so making a daily meditation become the way I kept the Rule. Developing a routine when I made took a healthy amount of effort: even though one is obliged to make a meditation of only a quarter of an hour each day, a solid 15 minutes of focused meditation does not come easy to a convert who was raised on MTV. I experimented with different times of the day (i.e. morning vs. evening vs. lunch hour), different locations (e.g. home vs. church vs. walks in the park), and different meditation books (e.g. Imitation of Christ vs. lives of the saints vs. Scriptures). I found that I consistently had the best success when I made my meditation first thing each morning (i.e. before breakfast) in my little living room oratory with the statue of our Lady; there I read a chapter from the Imitation, and then I reflected on the contents (on a Retreat the priests give good counsel on how to meditate well), after which I made a resolution for the day in which I asked for our Lady's help in applying some lesson or fruit gained from the reading and meditation. At first I was able to do this only sporadically -- in fact, when I began, all I could manage reading the chapter sans meditation; making a sustained reflection on it came only after a lot distracted effort (moderns are not exaggerating when they say the old rituals of the Faith do not hold their attention: they really do have trouble focusing on anything that is not some species of a paroxysm). After a Retreat I made a resolution to just grit my teeth and commit to keeping that schedule every morning for three weeks; by the time I'd kept this resolution for 21 days, I found that I had the solid beginnings of a new habit that have stayed with me ever since. Not only that, but the success in developing this new custom served as a beach-head for addressing other efforts in a consistent manner: e.g. morning and evening prayers, spiritual reading, daily examination of conscience, keeping the Lenten fast, and even mundane things like tackling difficult projects at work that I used to dread. On this last note, I have a current example: my manager is a militant atheist who finds it strange that I am a practicing Catholic; he has little good to say about the Catholic Church, he loves Obama, and he and I have several times had religious, philosophical, political, and moral discussions in which we profoundly disagree. And last week he told me that I was an extremely reliable worker in a business known for people not being reliable, and he encouraged me to go to our boss and ask for more money because of my performance on our projects together. I don't mean to suggest that developing a daily routine that involves a period of meditation is comparable to dealing with contrarian co-workers at the office, but conquering bad habits and acquiring good spiritual ones to replace them certainly served as a foundation for bigger battles that came after.