Right on spot. Find a regime for body and mind that you can sustain without any significant mental effort, after some time lack of good behavior be it sports of healthy food makes one uneasy. Bonus points from getting happy from it / making it a passion, this helps a lot with coming back after some hiatus (ie injury, sickness, long travel etc.).
Personal story - I used to be super sporty, 4x gym training during work week - cardio & free weights, climbing over evenings after work, hiking/climbing/ski touring over weekends. Vacations were mostly more extreme variants of the same. Last year broke my both ankles with paragliding, one leg much worse, so took me some 8 months to be able to walk straight again, with some time in wheelchair, then crutches. All strength & stamina gone, flexibility 0, so had to rebuild from scratch and I mean deep bottom scratch from which you bounce very slowly, not some 1 month stop when things come back quicker. If all above weren't my proper passions I would have a hard time coming back to being again more active than most(sans that paragliding, took the lesson and have 2 small kids). That ankle won't ever be same but so far so good, ie managed some serious hike&via ferrata mix 2 days ago.
Getting happy from it is 100% the most effective way to change habits.
Unfortunately it’s also very subjective and hard to find out what makes you happy…
Personal story - I used to be super sporty, 4x gym training during work week - cardio & free weights, climbing over evenings after work, hiking/climbing/ski touring over weekends. Vacations were mostly more extreme variants of the same. Last year broke my both ankles with paragliding, one leg much worse, so took me some 8 months to be able to walk straight again, with some time in wheelchair, then crutches. All strength & stamina gone, flexibility 0, so had to rebuild from scratch and I mean deep bottom scratch from which you bounce very slowly, not some 1 month stop when things come back quicker. If all above weren't my proper passions I would have a hard time coming back to being again more active than most(sans that paragliding, took the lesson and have 2 small kids). That ankle won't ever be same but so far so good, ie managed some serious hike&via ferrata mix 2 days ago.