I always say the phrase in my mind, everyday is everyday. There is something really powerful about doing something everyday, no matter what. I made a commitment to run 1 hour everyday. Well I just found out that I have a serious issue in my hips that needs to be dealt with. This complicates my commitment, so I cannot run like I was before. However, I can still go outside and run slowly or at least walk. Still get out there and do it, everyday.
Repetition is the answer. Many of your challenges with commitment get worked out with frequency. The more you engage, the more you build the muscle memory and the easier it comes to you. You can increase the difficulty over time, but that is not the point. Everyday is a commitment thing. So what I like to do is to get creative and figure out how I can manipulate my goals into a daily commitment.
This daily thing that I must do everyday becomes a commitment that I must do. It gives me something to do today, right now. It gives me forward progress, everyday. Imagine what life is like without this. You end up having a string of days with no productivity or even negative productivity. Your one day of goodness cannot withstand the damage from a string of non productive days. However, when you have daily commitments, you are doing something every single day and therefore gaining progress everyday even if it is just a little bit.