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.