If you find yourself doubting the benefits of sitting every day at 5:00am or perhaps you're rationalizing that missing just one day won't make any real difference over the span of 100, welcome to the oh so typical "commitment remorse" period. This quite common sense of doubt and regret about your resolution to create a new and beneficial habit is really an opportunity in disguise.
It's been my personal and vicarious experience that sometime between the 14th and 21st days of a new endeavor a rebellious toddler energy is evoked that disdains change. This "toddler" energy is comfortable with things as they are and fights tooth and nail to maintain the status quo. This is the opportunity for the burgeoning adult spirit within us to step in. The evolving adult within us needs to gently and firmly coax the toddler to do it in spite of the seeming inanity or discomfort of it all at the moment.
Within another 7-10 days, those rebellious sentiments seem to wither and fade away and a growing sense of freedom to choose and act in our self-interest bursts forth. This is the energy we embrace and which then propels us forward to complete the task.
Sit and enjoy your process...