For many years I have been saying that one thing I don't think I can be too legalist about is reading my Bible. Even when I don't want to. Even when I don't feel like I am growing. Even when I am in difficult sections of scripture to read.
I spent middle school, high school, and my first to years of college as a distance runner. One thing learned from my time as a runner is that running is as much a mental discipline as it is a physical one. Going on long runs prepares your mind mentally to know that you can do it, and running everyday regardless of how I feel moves me past the option to just rest one day...which turns into two...which turns into...
When I stopped running after my second year of college, I stopped running. Now 10 years later, I carry 40 more pounds than I did then, and my body is just not used to running consistently anymore. I really want to get back in shape and my goal is to run a marathon, but it is much more difficult now. The only solution for me, is to become legalistic about running. Knowing that everyday I will run take the option off the table to not. And over time I will get in shape again. Regardless of days that I don't want to do it or am not seeing the results I hoped or feel bad on the run, by running everyday I will reach my goal.
Sometimes reading my Bible is similar. Some days I don't want to. Some days I don't feel like I'm growing, but I know that by doing it consistently and making reading my Bible daily not optional, God will change my heart.
Here is a link to Piper's article.