Glad you came back to read this.

I struggle with this too, and I'm old. It is a difficult habit to break out of. I urge you to put a lot of effort into this, make "doing the things" your habit.

But most especially, forgive yourself if you don't do the thing. The best time to have done the thing is "already", and the second best time is "right now", and if you do the thing at the second best time right now, when you're done it will become the best.

Or, if you're having a hard time doing the thing, just do a small part of the thing. A sub-thing, as it were. "It's a little bit better than it was before."