My tips for the gym:
Do classes. Try to do at least 3 classes a week, and put them into your diary. Make it a routine.
Go to the gym before you do anything else. I have a demanding job with long hours, but mostly WFH. I sometimes think “Oh I’ll just do this task, write this report/ read this article” etc etc then I’ll go to the gym. That never works. I don’t go. And honestly, the time I take to go to the gym really doesn’t get in the way of my working productivity.
Have a routine - write it down. Then you don’t have to think. You just do it.
Just think in 5 minute slots, or 10 reps, or whatever. The joy of interval training, for example, is that you only need to do 1 minute, or 30 seconds or whatever, then rest/catch your breath/die, then do it again. For just a short interval.
the other thing that keeps me going to the gym is a fantastic PT. If you can afford it, it’s a really worthwhile investment. A good PT will teach you so much,and motivate you.
And really, just keep remembering how much better you feel after an hour of intensive exercise. It’s so so good for you, mentally and physically .