Reverting to prior habits isn't necessarily a failure if you look at all new things as experiments rather than unconditional commitments. Reversion can be very rational, especially when it amputates the sunk costs of failed experiments.
Perhaps the reason procrastination is such a prominent, time-tested feature of the human mind is that the current planning self is usually a poor spokesperson for one's future self.
Procrastination is your current actualized self passive aggressively getting back at your unrealistic past self. It's usually better if you can just punch your past self in the throat and move on.