Yeah, it's like a New Year's resolution... hard to keep up beyond the initial push. Personally, my solution to this was starting a collaborative log (via google docs.. which has a mobile app, phew) with my sister (same logic for any close friend or family member). You sacrifice some freedom of expression, but it keeps you both accountable, knowing that someone is expecting to read whatever you've written on a given day. It's also a great way to get feedback on your thoughts. Good luck!
The tendency to compartmentalize mind and body never made sense to me. The brain is adapted to navigating the physical world, so it should be unsurprising that physical exercise is a prerequisite to proper functioning. Why else would the "memory palace" be a thing? If our memory/perception is inherently spatial, then it relies on a privileged observer capable of interacting with its environment. The rest of the nervous system is basically just feeding you training data when you exercise.