How? I mean, one of my major symptoms is that I can't for life do either! "Training my body" doesn't feel like something natural or within range of possibility.
What do you mean by "natural or within range of possibility"?
One is consistent by doing, not by feeling (of course feelings have their own place in life). I don't enjoy going to the gym per se. I let go of that and go. I don't go because I feel happy and motivated before exercise. First, I went because people for thousands of years have saying so, and biologically it makes sense. Then, because I know how I feel in the short and long term after the exercise.
I do different sports for enjoyment and different for keeping in shape of course. I love hiking but going to a gym is more sustainable as a regular way of keeping in shape in all seasons and weather.
Just don't forget to be in the present.