When there is something that you want to do regularly (exercise, doing the final boring part of some sideproject, cleaning the house...) you remove willpower from the equation and set a day and a time.
For example, everyday from 18 to 19 I work on my sideprojects, or saturdays from 16 to 18 is house cleaning time. There is no question if I want to do it, it is set at that time and I have to do it, period.
The nice thing about routine is that the first times it is hard, but after some repetitions your mind (and body) begin to get used and it transforms into a routine and then it's like it's written in stone. That time period of that day X is for Y and it is what it is.
Routine can be used for bad things but also for good things.