As someone who's been there, and now leads an active lifestyle, I'd say it's best to avoid looking at things as black and white. The ability to build habits is

As someone who's been there, and now leads an active lifestyle, I'd say it's best to avoid looking at things as black and white. The ability to build habits is a skill you can learn, just as you can learn to ride a bike, program a computer, or cook a meal. It comes more or less naturally for different people, but if you can a fixed mindset instead of a growth mindset, it won't come at all. One lever I used was self hatred. Instead of babying myself, I decided I was pathetic and worthless if I couldn't even manage to exert myself for 10 minutes every day. Maybe not a psychologically healthy viewpoint in the long term, but it creates the leverage I needed to get out of that dark place.