Also basically programming in a nutshell.

Doable does not mean fun or worth doing.

(There are other effective ways to exercise and keep healthy than running. Find one that you find fun.)

But equally something being fun or worth doing doesn't mean you won't procrastinate doing it. Cleaning the house, for example, is definitely worth doing but many people procrastinate doing it, and it's actually a really good time to apply this technique:

You don't have to clean the whole house, you can just clean one room. You don't have to clean an entire room, you can just clean a bookcase. You don't have to clean the entire bookcase, you can just clean one shelf. You don't have to clean the entire shelf, you can just put one thing back in it's place. You don't even have to put it back, just go over and pick it up. ...

You can keep on going if none of those seem doable, right down to something like wiggling your big toe, but most people would probably at the very least find putting a single thing back doable.

And I've used an example of something that is worth doing but most people don't find fun, but there are plenty of examples of things that are both fun and worth doing that people still procrastinate (probably mostly occurs in mental health sufferers, but that was the entire point of my original comment).