I am very prone by nature to all our nothing thinking. There is something very appealing to having a clear apparant course of action, bright line rules and no discomfort that is the province of ambiguity.
It is arguable but questionable whether this type of thinking has served me well in my career. But it is indisputable that it has been a total disaster to my health and fitness. Brief but intensive devotion to "perfect" eating and slavish devotion to arbitrary and generic exercise regimens caused lots of short term gains and long tern destruction to my health as each moment of divine inspiration succumbed to the reality of the complexly personal way each of us has to address our fitness and our nutrition.
My advice is to not allow yourself to be seduced by the siren call of control and perfection as each of these objects are illusory. Through much trial and error and much failure over the years, I have come to find the secret of become fit, healthy and happy: compassion and love -- for yourself.
I firmly believe that no one has ever succeeded in the long term at loathing themselves into a fit, healthy body. This feeling that unless we are thin and fit, we are not enough, is what propels the all or nothing thinking that gives us that satisfying but ephemeral illusion of control. Don't fall for it.
Instead, build a series of practices that support self esteem and a healthy mind-body connection and attitude. Consider adding a yoga practice or a daily meditation practice in order to increase your mindfulness as to why you deserve to be fit, healthy and happy. Find a community of positive people to help keep you positive when that inner voice speaks in an unforgiving and uncompassionate manner.
Don't fall into the trap of all or nothing thinking. You deserve better.